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CHAPTERS
IN
POPULAR NATURAL
HISTORY.
BY
Sir JOHN LUBBOCK, Bart., M.P., F.R.S.,
D.C.L., LL.D., PRES. LINN. SOC, ETC., ETC., ETC.
ARRANGED AS AN AD VANCED READING BOOK FOR
USE IN ELEMENTARY AND HIGHER SCHOOLS.
London :
NATIONAL SOCIETY'S DEPOSITORY,
Sanctuary, Westminster.
[All rights resei-ved.]
LONnoN :
HAkKISON AND SONS, PRINTERS IN ORDINARY TO HER MAJESTY,
sr. MARTIN'S LANE.
PREFACE.
The National Society has done me the honour
to propose to republish parts of some of my Natural
History Lectures adapted as a Reading Book.
Those who may wish to pursue the subjects
further, I would refer to my " Origin and Metamor-
phoses of Insects" (Macmillan and Co.), "British
Wild Flowers," &c. (Macmillan and Co.), " Scientific
Lectures" (Macmillan and Co.), and "Ants, Bees,
and Wasps" (Paul, Trench, and Co.).
I am greatly indebted to my publishers for their
courtesy in allowing me to reprint here part of the
above-mentioned works.
I have also to thank Messrs. Paul, Trench, and Co.,
Messrs. Macmillan and Co., Messrs. Cassell and Co.,
and Messrs. Lovel Reeve and Co., for the use of
various illustrations, which they have been so good
as to place at my disposal.
High Elms, Down, Kent.
Dac/nbn; 1882.
CONTENTS.
SECTION I.
Ants
SECTION II.
Bees and Wasps
t
SECTION III.
The Colours of Animals
. . SECTION IV.
On Flowers and Insects
SECTION V.
On Plants and Insects
SECTION VI.
Fruits and Seeds
LIST OF ILLUSTRATIONS.
FIG.
1. The Slave-making or Amazon Ant (Polyergus rtcfcscens).
2. Larva, Chrysalis, and Cocoon of the Horse Ant {Formica rufa).
After Blanchard.
3. The Horse Ant {Formica rufa) : Male, Female, and Worker.
After Blanchard.
4. The Mexican Honey Ant {Myr77iecocystus mexica?ms). After
Blanchard.
5. The Sauba Ant {Oecodoma cephalotes). Two sisters.
6. The Rose Aphis {Aphis Rosce). After Blanchard.
7. A Root-feeding Aphis.
8. The White Woodlouse {Platyarthrus hofftnanseggii) + lo. After
Spence Bate.
9. Claviger. After Shuckard.
10. The Slave Ant {Fonnica fusca).
11. The Caterpillar of the Marbled White Butterfly {Arge galathea).
After Weissmann.
12. The Caterpillar of the Eyed Hawk-moth {Smerinthus ocel-
latus). After Weissmann.
13. The Caterpillar of the Elephant Hawk-moth {Cheerocampa
elpenor). Full grown, natural size. After Weissmann.
14. The Caterpillar of the Elephant Hawk-moth {Chccrocampa
elpenor). First Stage. After Weissmann.
15. The Caterpillar of the Elephant Hawk-moth {Charocampa
elpenor). Second Stage. After Weissmann.
16. The Caterpillar of the Elephant Hawk-moth {Charocampa
elpenor). Just before the second moult. After Weissmann.
17. The Caterpillar of the Elephant Hawk-moth {Charocampa
elpenor). Third Stage. After Weissmann.
L ist of Illustrations.
FIG.
i8. The Caterpillar of the Elephant Hawk-moth (Ch<vrocami>a
elpejior). Fourth Stage. After Weissmann.
19- The Caterpillar of the Elephant Hawk-moth. {Charocampa
elpenor). Fifth Stage. After Weissmann.
20. The Caterpillar of the Small Elephant Hawk-moth {Chcerocamja
porcellus). After Weissmann.
21. White Deadnettle {Lamium album). After Bentham.
22. Flower of White Deadnettle (Lamium album).
23. Section of the Flower of White Deadnettle [Lamium album).
24. Meadow/ Gexz.nmm [Geranium pratettse). After Bentham.
25. Common Sundew [Drosera rohindijolia). After Bentham.
26. Common Bladderwort (d7?r(Vz</ar/a z;?//^<2w). After Bentham.
27. Broad Dock [Rumex obtttsifolius). After Bentham.
28. Common Willow Herb [Epilobium angusti/olium). After
Bentham.
29. Common Mallow [Malva sylvestris). After Sowerby.
30. Dwarf Mallow [Malva rotundifolia). After Sowerby.
31. Stamens and Stigmas of the Common Mallow [Malva sylves-
tris). After Miiller.
32. Stamens and Stigmas of the Dwarf Mallow [Malva rotundifolia).
After Miiller.
33. Common Willow Herb [Epilobium angusti/olium). After
Sowerby.
34. Hoary Willow Herb [Epilobium parviflorum). After Sowerby.
35. Meadow Geranium [Geranium pratense). Young flower and
older flower. After Hildebrand.
36. Common Arum [Arum maculatufn). Diagrammatic section.
37. Sage [Salvia officinalis). Section of a young flower. After Ogle.
38. Sage [Salvia officinalis) visited by a Bee. After Ogle.
39. Si&ge [Salvia officinalis). Section of an older flower. After Ogle.
40. Stamens of Sage [Salvia officinalis) in their natural position.
After Ogle.
41. Stamens of Sage [Salvia officinalis) when moved by a Bee.
After Ogle.
42. y^'M Chervil [Cluerophylhitn sylveslre). After Bentham.
43. Floret of Feverfew ( Chrysant/icmtim parthenium). Just opened.
After Ogle.
List of ]/histraiions.
vii
FIG.
44. Floret of Feverfew {Chrysanthemum patihenium). Somewhat
more advanced. After Ogle.
45. Floret of Feverfew (Chrysanthemum parthenium). With . the
stigmas expanded. After Ogle.
46. Bird's-foot Trefoil {Lotus cornicutatus). After Bentham.
47. Flower of Bird's-foot Trefoil {Lotus cornicutatus), seen from the
side and in front. After Midler.
48. Flower of Bird's-foot Trefoil {Lotus comiculatus), after removal
of the standard. After Miiller.
49. Flower of Bird's-foot Trefoil {Lotus coj-nicitlatus), after removal
of the standard and wings. After Miiller.
50. Flower of Bird's-foot Trefoil {Lotus comiculatus), after removal
of one side of the keel. After Miiller.
51. Flower of Bird's-foot Trefoil {Lotus corniculattts). Terminal
portion of fig. 50, more magnified. After Miiller.
52. Common Cowslip {Primula veris). After Bentham.
53. Section of the Flower of Primula. Long-styled form.
54. Section of the Flower of Primula. Short-styled form.
55. Common Carlina {Carlina vulgaris). After Kerner.
56. Ktiatttia dipsacifolia. After Kerner.
57. Flower of Linnssa. After Kerner.
58. Amphibious Polygonum {Polygotium ampliibititn). After
Bentham.
59. Nottingham Catchfly {Sikfie mitans). After Bentham.
60. Nottingham Catchfly {Silc7ie nutans). After Kerner.
61. John Go-to-Bed-at-Noon {Tragopogonpratense). After Bentham.
62. Valisneria {Valisjieria).
63. Hairy Bittercress (CWa/ww /«>j«/a). After Bentham.
64. Hairy Violet ( Viola hirta).
65. Dog Violet ( Viola camna).
66. Dog Violet {Viola canina). Seed-vessel open and showing
seeds.
67. Dog Violet ( Viola canina). Seed-vessel after ejecting the seeds.
68. Herb Robert {Geranium Robertianum).
69. Cut-leaved Geranium {Geranium dissectum). Diagram.
70. Herb Robert {Geranium Robertianum). Diagram.
7J. Wood Vetch {Vicia sylvatica).
viii
List of Illustrations.
FIG.
72. Pod of Bush Vetch ( Vicia sepitm). After Bentham,
73- Fi-uit of the Squirting Cucumber {Ecballium).
74. Poppy-head {Papaver).
75. Seeds or Fruits of the Maple, Sycamore, Lime, Hornbeam,
Elm, Birch, Pine, Fir, Ash.
76. Fruits or Seeds of the Willow Herb (EpiMiu?n), Hawkbit
{Thrincia hiria), Tamarix, Willow {Salix), Cotton-grass
{Eriophorutn), Bullrush ( Typha).
77. Lesser Duckweed {Lemna minor). After Bentham.
78. Seeds or Fruits of Burdock {Lappa), Agrimony {Agrimonia),
Bur Parsley {Caucalis), Enchanter's Nightshade {Circcea),
Cleavers {Galium), Forget-me-not {Myosotis).
79. Fruits of Harpagophyton procumbens and Martynia proboscidea.
Natural size.
80. Seed of Myzodendron. After Hooker.
81. Cardamhte che7topodifolin7n.
82. Vetch ( Vicia amphicarpa).
83. Pea {Lathyrus a?nphicafpos).
84. Seed of Crane's Bill {Erodium).
85. Seed of Stipa pentiata. Natural size.
86. Seeds of Corydalis.
87. Pods of Scorpiuriis siibvillosa and Scorpiurus vermicidata.
88. Pod of Biserrula.
89. Seed of Castor Oil Plant.
90. Seed of Jatropha.
CHAPTERS
IN
POPULAR NATURAL HISTORY.
Fig. I. — The Slave-making Ant.
SECTION I.-ANTS.
I.
I. There is no animal or plant which would not
well repay long and careful study. Yet all are by
no means equally interesting. Some specially de-
2
Ants.
serve attention from their utility to man, some
from their power of inflicting injury. Among
insects there are few, if any, whose habits are
more interesting than those of Ants. They Hve in
large communities : they build houses ; they make
roads ; some of them, as we shall presently see,
keep other insects, just as we keep cows ; and some
of them even have slaves.
In this country we have rather more than thirty
kinds ; but ants become more numerous in species,
as well as in individuals, in warmer countries, and
more than a thousand species are known. Even
this large number is certainly far short of those
actually in existence.
2. No two species of ants are identical in habits ;
and, on various accounts, their mode of life is far
from easy to unravel. Most of their time is passed
underground ; all the tending of the young, for
instance, is carried on in the dark. I have for
some years kept many nests of various species
under observation, and these have given me special
facilities for observing the internal economy of
ant Hfe. Another main difference between my
observations and those of previous naturalists has
consisted in the careful record of the actions of
individual ants. The most convenient mode of
marking them was, I found, a small dab of paint
on the back.
3. The life of an ant falls into four well-marked
periods — those of the egg, of the larva or grub
A Jits.
3
(fig-. 2, a a'), of the pupa or chrysalis (fig. 2, i) d')
and of the perfect insect or imago. The eggs
are white or yellowish, and somewhat elongated.
B 2
4
Anis.
They are generally said to be hatched about fifteen
days after being laid, but those observed by me
have taken a month or six weeks.
The larvae or grubs of ants, like those of bees
and wasps, are small, white, legless creatures, some-
what conical in form, narrowing towards the head.
They are carefully tended and fed, being carried
about from chamber to chamber by the workers,
probably in order to secure the most suitable
amount of warmth and moisture. I have observed,
also, that they are very often assorted according to
age. It is sometimes very curious in my nests to
see them arranged in groups according to size, so
that they remind one of a school divided into five
or six classes.
4. As regards the length of life of the larvae,
those which are born in the spring become full
grown in a few weeks. In other cases the period
is much longer. In certain species — the small
yellow Meadow Ant, for instance — some of the
larvae live through the winter.
When full grown the larvae turn into pupae,
sometimes naked (fig. 2, 1? b'), sometimes covered
with a silken cocoon (fig. 2, cc'), constituting the
so-called "ant-eggs." We do not yet understand
why some larvae spin cocoons, while others remain
naked. As a general rule, the species which
have a sting are naked, Avhile those which have
not are enveloped in a cocoon. There is, however,
one species the larvae of which sometimes spin
Ants.
5
a cocoon, and sometimes remain naked. The
reason for this difference is still quite unknown.
After remaining some days in the pupa state
they emerge as perfect insects. In many cases,
however, they would perish in the attempt if they
were not assisted ; and it is very pretty to see the
older ants helping them to extricate themselves,
carefully unfolding their legs and smoothing out
their wings, with truly feminine tenderness and
delicacy.
5. In the case of ants, as with other insects which
pass through similar metamorphoses — such as bees,
wasps, moths, butterflies, flies, beetles, &c. — the
larval stage is the period of growth. During the
chrysalis stage, though immense changes take
place, and the organs of the perfect insect are more
or less rapidly developed, no food is taken, and
there is no addition to the size or weight.
The imago or perfect insect again takes food,
but does not grow. The ant, like all the insects
above named, is as large when it emerges from the
pupa as it ever will be, though the abdomen of the
females sometimes increases in size from the deve-
lopment of the eggs.
6. We have hitherto had very little information as
to the length of life in ants in the imago, or perfect,
state. So far, indeed, as the preparatory stages
are concerned, there is little difiiculty in approxi-
mately ascertaining the fads; namely, that while
in summer the larval condition lasts only a few
6
A Jits.
weeks, in some species, as in our small yellow
Meadow Ants, the autumn larvs remain with com-
paratively little change throughout the winter. It
IS much more difficult to ascertain the length of
hfe of the perfect insects, on account of their gre-
garious habits, and the difficulty of recognising
individual ants. I have found, however, as we
shall presently see, that their life is much longer
than has been generally supposed; and I have
now two ants which are more than nine years old.
I have kept in captivity about half of our British
species of ants, as well as a considerable number of
foreign forms, and for the last few years have
generally had from thirty to forty communities
under observation.
7. Some ants have a sting ; some bite with their
jaws, and then squirt poison into the wound. In-
deed, in some cases the poison is sufficiently strong
itself to cause a wound. Moreover, some species
have the power of ejecting their poison to a con-
siderable distance. In Switzerland, after disturbing
a nest of the Horse Ant, I have found that a hand
held as much as 18 inches above the ants was
covered with acid. But even when the poison is
not thus fired, as it were, at the enemy from a dis-
tance, there are two cases in which the stinsr mieht
be allowed to fall into disuse. Firstly, those species
which fight with their mandibles might find it on the
whole most convenient to inject the poison (as they
do) into the wounds thus created. Secondly, if
Ants.
7
the poison itself is so intensified in virulence as to
act through the skin, a piercing instrument would
be of comparatively small advantage. I was
amused one day by watching some specimens of a
small species of ant, which were feeding on some
drops of honey. Some ants of a larger kind were
anxious to share the feast, but the moment one
approached, the little ones simply threatened them
with the tip of their tail, and the large ones imme-
diately beat a hasty retreat. In this case the
comparatively large kind could certainly have had
nothing to fear from physical violence on the part
of the httle ones. Mere contact with the poison,
however, appeared to cause them considerable
pain ; and generally the threat alone was sufficient
to cause a retreat.
8. flowever this may be, in their modes of fight-
ing different species of ants have their several pecu-
liarities. Some are much less military than others.
Jlfyrmedna Latreillii, for instance, never attack,
and scarcely even defend themselves. Their skin
is very hard, and they roll themselves into a ball,
not defending themselves even if their nest is in-
vaded ; to prevent which they make the entrances
small, and often station at each a worker, who uses
her head to stop the way. The scent of this
species is also, perhaps, a protection. Tetramorium
ccespitum has the habit of feigning death. This
species, however, does not roll itself up, but merely
applies its legs and antennae closely to the body.
8
Ants.
Formica rufa (fig. 3), the common Horse Ant,
attacks in serried masses, seldom sending out de-
tachments, while single ants scarcely ever make
individual attacks. They rarely pursue a flying foe,
but give no quarter, killing as many enemies as
Ants.
9
possible, and never hesitating to sacrifice themselves
for the common good.
9. Formica sajigiiinea, on the contrary, though
very like the Horse Ant in appearance, is very dif-
ferent in habits. It is a slave-making species, and
in their military expeditions, they attempt rather
to terrify than to kill. Indeed, when invading a
nest, they do not attack the flying inhabitants un-
less these are attempting to carry off pupae, in
which case the F. sanguinea force them to abandon
the pups. When fighting, they attempt to crush
their enemies with their mandibles.
10. Formica exsecta is a delicate, but very active
species. They also advance in serried masses, but
in close quarters they bite right and left, dancing
about to avoid being bitten themselves. When
fighting with larger species they spring on to their
backs, and then seize them by the neck or by an
antenna. They also have the instinct of acting
together, three or four seizing an enemy at once,
and then pulling different ways, so that she on her
part cannot get at any one of her foes. One of
them then jumps on her back and cuts, or rather
saws, off her head. In battles between this ant
and the much larger F. pratensis, many of the
F. exsecta may be seen on the backs of the F. pra-
tensis, sawing off their heads from behind.
ir. The ants of the different species of Lasius
make up in numbers what they want in strength.
Several of them seize an enemy at once, one by
lO
Ants.
each of her legs or antennae, and when they have
once taken hold they will suffer themselves to be
cut in pieces rather than leave go.
The Amazon Ant, which, like Formica sanguinea,
is a slave-making species, has a mode of combat
almost peculiar to herself The jaws are very
powerful and pointed. If attacked— if, for in-
stance, another ant seizes her by a leg — she at
once takes her enemy's head into her jaws, which
generally makes her quit her hold. If she does
not, the ant closes her mandibles, so that the
points pierce the brain of her enemy, paralysing
the nervous system. The victim falls in convul-
sions, setting free her terrible foe. In this manner
a comparatively small force will fearlessly attack
much larger armies of other species, and suffer
themselves scarcely any loss.
II
I. Under ordinary circumstances an ants' nest,like
a beehive, contains three kinds of individuals (fig. 3):
12
Ants.
workers or imperfect females (which constitute the
great majority), males, and perfect females. There
are often, however, several queens in an ants' nest ;
while, as we all know, there is never more than one
queen mother in a hive. The queens of ants are
provided with wings, but after a single flight they
tear them off, and do not again quit the nest. In
addition to the ordinary workers, there is in some
species a second, or rather a third, form of female.
In almost any ants' nest we may see that the
workers differ more or less in size. The amount of
difference, however, depends upon the species. In
the small brown Garden Ant, the workers are, for
instance, much more uniform than in the little
yellow Meadow Ant, or in the Harvesting Ant,
where some of them are much more than twice as
large as others. But in certain ants there are
differences still more remarkable. Thus, in a
Mexican species (fig. 4), besides the common
workers, which have the form of ordinary neuter
ants, there are certain others in which the abdomen
is swollen into an immense sphere. These indi-
viduals are very inactive, and serve principally as
living honey-jars. They receive the honey from the
foragers, retain it unaltered in their crop, and feed
their companions when fresh food falls short. In
another kind, very common in Southern Europe,
there are also two distinct forms without any
intermediate gradations ; one with heads of the
usual proportion, and a second with immense heads
Ants.
13
provided with very large jaws. The large-headed
individuals are generally supposed to act as sol-
diers, and the size of the head enables the muscles
which move the jaws to be of unusual dimensions ;
but the little workers are also veiy pugnacious.
2. Bates tells us that in the marching columns of
EcitoJi (a kind of South American ant) the large-
headed workers " all trotted along empty-handed
and outside the column, at pretty regular intervals
from each other, like subaltern officers in a march-
ing regiment ... I did not see them change their
position, or take any notice of their small-headed
comrades ;" and he says that if the column was
disturbed they appeared less pugnacious than the
others.
In the Sauba Ant of South America there are
five distinct kinds of individuals. I have figured
two (fig. 5). They are sisters, and of the same age,
but so unlike one another that one would hardly
suppose they belonged to the same species. No
doubt they perform different duties. It has been
supposed that the large ones act as soldTers, but
the reason for the difference between the different
kinds of workers is still uncertain.
3. For some little time after arriving at maturity,
ants devote themselves exclusively to the care of the
larvae and pup^e, and take no share in the defence
of the nest or other out-of-door work until they
are some days old. This seems natural, because
at first their skin is comparatively soft ; and it
Fig. 5.— The Sauba Ant {Oecodoma cep/talo.'es).
Two sisters. Magnified four times.
Aiits.
would clearly be undesirable for them to undertake
rough work or run into danger until their armour
had had time to harden. There are, however,
reasons for thinking that the division of labour is
carried still further. I do not allude merely to
those cases in which there are completely different
kinds of workers, but also to the ordinary workers.
In the yellow Meadow Ant, for instance, it seems
probable that the duties of the small workers are
rather different to those of the large ones, though
no such division of labour has yet been detected.
I have myself made some further observations
pointing in the same direction.
i6
Aiits.
III.
I. The nests of ants may be divided into several
classes. Some species, our common Horse Ant for
instance, collect large quantities of materials, such
as bits of stick, fir leaves, &c., which they heap up
into conical masses. Some construct their nests of
earth, the cells being partly above, partly below,
the natural level. Some are entirely underground,
others eat into the trunks of old trees.
In some cases the nests are very extensive.
Bates mentions that while he was at Para an attempt
was made to destroy a nest of the Sauba Ants by
blowing into it the fumes of sulphur, and he saw
the smoke issue from a great number of holes, some
of them not less than 70 yards apart.
2. A community of ants must not be confused
with an ant hill in the ordinary sense. Very often,
indeed, a community has only one dwelling, and in
most species seldom more than three or four.
Some, however, form numerous colonies. M. Forel
even found a case in which one community had no
less than 200 colonies, and occupied a circular
space with a radius of nearly 200 yards. Within
this area they had destroyed almost all the other
ants. In these cases the number of ants thus asso-
ciated together must have been enormous. Even
Ants.
in single nests Forel estimates the numbers at
from S,ooo to 500,000.
Ants also make for themselves roads. These
are not merely worn by the continued passage of
the ants, as has been supposed ; but are actually
prepared by the ants, rather, however, by the
removal of obstacles than by any actual construc-
tion. In some cases these roadways are arched
over with earth, so as to form covered ways. In
others, the ants excavate regular subterranean
tunnels, sometimes of considerable length.
3. The food of ants consists of insects, great
numbers of which they destroy ; of honey, honey-
dew, and fruit — indeed, scarcely any animal or sweet
substance comes amiss to them. Some species —
such, for instance, as the small brown Garden Ant
— ascend bushes in search of aphides (fig. 6).
The ant then taps the aphis gently with her
antennae, and the aphis emits a drop of sweet
fluid, which the ant drinks. Sometimes the ants
even build covered ways up to and over the
aphides, which, moreover, they protect from the
attacks of other insects. Our English ants do not
store up provision for the winter ; indeed, their
food is not of a nature which would admit of this.
4- Ants have many enemies. They themselves,
and still more their young, are a favourite food of
many animals. They are attacked also by nume-
rous parasites. If a nest of the brown ant is
disturbed at any time during the summer, some
C
i8
Ants.
small flies may probably be seen hovering over the
nest, and every now and then making a dash at
<
o
g
5
a
w
o
some particular ant. These flies lay their eggs on
the ants, inside which the larvje live. Other
An is.
19
species of the genus are in the same way parasitic
on bees. Ants are also sometimes attacked by-
mites. On one occasion I observed that one of
my ants had a mite attached to the underside of
its head. The mite, which maintained itself for
more than three months in the same position, was
almost as large as the head of the ant. The ant
could not remove it herself Being a queen, she did
not come out of the nest, so that I could not do it
for her ; and none of her own companions thought
of performing this kind office.
5. In character the different species of ants
differ very much from one another. F. fusca, the
one which is pre-eminently the " Slave " Ant, is, as
might be expected, extremely timid ; while the
nearly allied F. cinerea has, on the contrary, a
considerable amount of individual audacity. F.
rufa, the Horse Ant, is, according to M. Forel,
especially characterised by the want of individual
initiative, and always moves in troops ; he also
regards the genus Formica as the most brilliant,
though others excel it in other respects — as, for
instance, in the sharpness of their senses. F. pra-
tensis worries its slain enemies; F. sanguinea
never does so. The Amazon Ant is, perhaps, the
bravest of all. If a single individual finds herself
surrounded by enemies she never attempts to fly, as
any other ant would, but transfixes her opponents
one after another, springing right and left with
great agility, till at length she succumbs, over-
c 2
20
Ants.
powered by numbers. Myrmica scabrinodis is
cowardly and thievish; during wars among the
larger species they haunt the battle-fields and
devour the dead. Tetramorium is said to be very
greedy ; Myrmecifta very phlegmatic.
6. In industry ants are not surpassed even by
bees and wasps. They work all day, and in warm
weather, if need be, even at night too. I once
watched an ant from six in the morning till a
quarter to ten at night, and she worked without
intermission the whole time. I had put her to a
saucer containing larvae, and in this time she
carried off no less than 187 to the nest. I kept
another ant which I employed in my experiments,
under observation several days. When I had to
leave the house, and again when I went to bed at
night, I kept her shut up in a small bottle, but the
moment I let her out she began to work again.
On one occasion I was away from home for a week.
On my return I took her out of the bottle, placing
her on a little heap of larvae about three feet from
the nest. Under these circumstances I certainly
did not expect her to return. However, though
she had thus been six days in confinement, the
brave little creature immediately picked up a larva,
carried it off to the nest, and after half an hour's
rest returned for another.
7. Our countryman Gould noticed certain
"amusements" or "sportive exercises" which he
had observed among ants. Huber also mentions
Ants.
21
scenes which he had witnessed on the surface of ant
hills, and which, he says, " I dare not qualify with
the title gymnastic, although they bear a close re-
semblance to scenes of that kind." The ants raised
themselves on their hind legs, caressed one another
with their antennae, engaged in mock combats, and
almost seemed to be playing at "hide and seek."
Forel entirely confirms Ruber's statements, though
he was at first incredulous.
8. Lastly, I may observe that ants are very
cleanly animals, and assist one another in this re-
spect. I have often seen them licking one another.
Those, moreover, which I painted for facility of
recognition were gradually cleaned by their friends.
Though ants have not influenced the present
condition of the vegetable kingdom to the same
extent as bees, yet they also have had a very
considerable effect upon it in many ways.
Our European ants do not strip plants of their
leaves. In the tropics, on the contrary, some
species do much damage in this manner.
9. There are, of course, many cases in which the
action of ants is very beneficial to plants. They
kill off a great number of small caterpillars and
other insects. Forel found in one large nest that
more than 28 dead insects were brought in per
minute, which would give during the period of
greatest energy more than 100,000 insects destroyed
in a day by the inhabitants of one nest alone.
22
Fig. 7, — Root-feeding Aphis.
IV.
1. As already mentioned, none of our northern
ants store up grain, and hence there has been
much discussion as to the well-known passage of
Solomon. I have, however, observed that the small
brown ants sometimes carry seeds of the violet into
their nests, but for what purpose is not clear. It
is, however, now a well-established fact that more
than one species of southern ants do collect seeds
of various kinds. The fact, of course, has long
been known in those regions.
2. A Texan Ant is also a harvesting species,
storing up especially the grains of the so-called "ant-
Ants.
23
rice" and of a grass. These ants clear disks, 10 or
12 feet in diameter, round the entrance to their nest
a work of no small labour in the rich soil, and
under the hot sun, of Texas. I say " clear" disks,
but some, though not all, of these disks are occu-
pied, especially round the edge, by a growth of
ant-rice. It seems evident that the disks are kept
carefully clean, that the ant-rice alone is permitted
to grow on them, and that the produce of this crop
is carefully harvested ; but it is possible that the
ant-rice sows itself, and is not actually cultivated
by the ants. I have myself observed in Algeria,
that certain plants are allowed by the ants to grow
on their nests while others are destroyed.
3. The relations existing between ants and other
animals are even more interesting than their rela-
tions with plants. As a general rule — not, however,
without many remarkable exceptions — they may be
said to be those of deadly hostility.
Though honey is the principal food of ants they
are very fond of meat, and in their wild state
ants destroy large numbers of other insects. Our
English ants generally go out hunting alone, but
many of the species living in hotter climates hunt
in packs, or even in troops.
4. Savage has given a graphic account of the
" Driver" Ants of West Africa. They keep down,
he says, "the more rapid increase of noxious in-
sects and smaller reptiles ; consume much dead
animal matter, which would otherwise become
24
Ajiis.
offensive, and thus vitiate the atmosphere • and
often compel the inhabitants to keep their dwell-
ings, towns, and their vicinity in a state of
comparative cleanliness."
These ants will soon destroy even the largest
animal if it is confined. In one case Savage saw
them kill near his house a snake four feet long.
Indeed, it is said that they have been known to
destroy the great boa, when gorged with food and
powerless. The natives even fancy that the
python, after crushing its victim, does not venture
to swalloAV it, until it has made a search, and is
satisfied that there are no "Drivers" in the vici-
nity ! It is very remarkable that these hunting ants
are blind. They emerge, however, principally by
night, and, like some of the blind hunting ants of
Brazil, prefer to move under covered galleries, which
they construct rapidly as they advance.
5. It has long been known that ants derive a very
important part of their sustenance from the sweet
juice excreted by aphides. The ants may be said,
almost literally, to milk the aphides ; for the aphides
generally retain the secretion until the ants are
ready to receive it. The ants stroke and caress
the aphides with their antennae, and the aphides
then emit the sweet fluid. These insects, in fact,
as has been over and over again observed, are
the cows of the ants.
The different species of ants utilise different
species of aphis. The common brown Garden Ant
A /lis.
25
devotes itself principally to the aphides (fig. 6)
which frequent twigs and leaves ; another kind to
the aphides which live on the bark of trees ; while
the little yellow ant keeps flocks and herds of the
aphides which feed on the roots of grasses (fig. 7).
6. As the honey of the aphides is more or less
sticky, it is probably an advantage to the aphis
that it should be removed. Nor is this the only
service which ants render to them. They protect
them from the attacks of enemies ; and not un-
frequently even build cowsheds of earth over them.
The Yellow Ants collect the root-feeding species
(fig. 7) in their nests, and tend them as carefully as
their own young. But this is not all. The ants not
only guard the mature aphides, which are useful ;
but also the eggs of the aphides, which of course,
until they come to maturity, are quite useless.
7. I first met with these eggs in February, 1876,
and found that the ants took great care of them,
carrying them off to the lower chambers with
the utmost haste when the nest was disturbed.
I brought some home with me and put them near
one of my own nests, when the ants carried them
inside. That year I was unable to carry my obser-
vations further. In 1877 I again procured some of
the same eggs, and offered them to my ants, who
carried them into the nest, and in the course of
March I had the satisfaction of seeing them hatch
into young aphides.
8. When myeggs hatched I naturallythought that
26
A7iis.
the aphides belonged to one of the species usually
found on the roots of plants in the nests of the
ants. To my surprise, however, the young crea-
tures made the best of their way out of the nest,
and, indeed, were sometimes brought out by the
ants themselves. In vain I tried them with roots
of grass, &c. ; they wandered uneasily about, and
eventually died. Moreover, they did not in any
way resemble the subterranean species. In 1878 I
again attempted to rear these young aphides ; but
though I hatched a great many eggs I did not
succeed. In 1879, however, I was more fortunate.
The eggs commenced to hatch the first week in
March. Near one of my nests, in which I had
placed some of the eggs in question, was a glass
containing living specimens of several species of
plant commonly found on or around ants' nests.
To this some of the young aphides were brought
by the ants. Shortly afterwards I observed on a
plant of daisy, in the angles of the leaves, some
small aphides, very much resembling those from
my nest, though we had not actually traced them
continuously. They seemed thriving, and remained
stationary on the daisy. Moreover, whether they
had sprung from the black eggs or not, the ants
evidently valued them, for they built up a wall of
earth round and over them. So things remained
throughout the summer ; but on the 9th October I
found that the aphides had laid some eggs exactly
resembling those found in the ants' nests ; and on
Ants.
27
examining daisy-plants from outside, I found on
many of them similar aphides, and more or less of
the same eggs.
9. Our ants, then, though they may not perhaps
lay up food for the winter, do more, for they keep
during six months the eggs which will enable them
to procure food during the following summer — a
case of prudence unexampled in the animal
kingdom.
The nests of our Common Yellow Ant contain
in abundance four or five species of aphis, more
than one of which appears to be as yet undescribed.
In addition, however, to the insects belonging to
this family, there are a large number of others
which live habitually in ants' nests, so that we
may truly say that our English ants possess a much
greater variety of domestic animals than we do
ourselves. Large nests of the Horse Ant some-
times contain at least a thousand of such guests ;
and I believe that the aphides in a nest of the
little yellow ant would often be much more nume-
rous. We now know of no less than 584 species of
insects, which are habitually found in association
with ants, and of which 542 are beetles.
10. The association of some of these insects with
ants may be purely accidental and without signifi-
cance. In some of them no doubt the bond of
union is merely the selection of similar places of
abode ; in some few others the ants are victimized
by parasites of which they cannot rid themselves.
28
A7its.
Then there are some insects, such as the caterpillar
of that beautiful beetle, the rosechafer, which find a
congenial place of residence among the collection
of bits of stick, &c, with which certain species of
ants make their nests.
1 1. Another class of ant guests are those which
reside with the ants actually in their galleries
and chambers, but which the latter never touch.
Of these the commonest in England are a species
for which I have proposed the name Beckia. They.
Fig. 8. — White WOODLOUSE {Platyarthrus koffmanseggti). + lo.
are active bustling little beings, and I have kept
hundreds, I may say thousands, in my nests. They
run about in and out among the ants, keeping their
antennas in a perpetual state of vibration. Another
very common species is a sort of white woodlouse
(fig. 8). Both of these, from living constantly in the
dark, have become blind ; I say " have become,"
A Jits.
29
because their ancestors no doubt had eyes. In
neither of these cases have I ever seen an ant
take the sUghtest notice of either of these insects.
One might almost imagine they had the cap of
invisibihty.
12. It is certain that the ants (if I may so say)
sanction the residence of these insects in their
nests. An unauthorised interloper would be at
once killed. I have, therefore, ventured to suggest
that these insects may, perhaps, act as scavengers.
In other cases the association is more close, and
the ants take the greatest care of their guests.
It appears that many of these insects produce
a secretion which serves as food for the ants.
This is certainly the case, for instance, with a
curious beetle (fig. 9), which is quite blind, and
appears to be absolutely dependent upon the ants.
It even seems to have lost the power of feeding
itself ; at any rate, it is habitually fed by the ants,
Fig. 9. -Claviger.
3° Ants.
who supply it with nourishment as they do one
another. Muller saw the ants caressing the beetles
with their antenna.. These beetles have certain
tufts of hairs (fig. 9, d) at the base of the wingcases
and the ants take these tufts into their mouths and
hck them, as well as the whole upper surface of
the body, with apparently the greatest enjoyment
A nts.
31
Fig. 10. — The Slave Ant {Formica Jusca).
V.
I. It is hardly necessary to say that, as a general
rule, each species of Ant lives by itself. There are,
however, some interesting exceptions. One little
kind of ant is found exclusively in the nests of the
much larger Horse Ants. We do not know what
the relations between the two species are ; the small
ones, however, follow the Horse Ants when they
change their nest, running about among them and
between their legs, tapping them inquisitively with
their antennae, and even sometimes climbing on to
their backs, as if for a ride, while the large ants seem
to take little notice of them. They almost seem to
be the dogs, or perhaps the cats, of the ants.
Another small species, which makes its chambers
and galleries in the walls of the nests of larger
32
Aiiis.
species, is the bitter enemy of its hosts. The latter
cannot get at them, because they are too large to
enter the galleries. The little ones, therefore, are
quite safe, and, as it appears, make incursions 'into
of tlic l3.rj^d
ant, and carry off the
larvae as food. It is as if we had small dwarfs,
about 1 8 inches to 2 feet long, harbouring in the
walls of our houses, and every now and then
carrying off some of our children into their horrid
dens.
2. Most ants, indeed, will carry off the larvce and
pupae of others if they get a chance ; and this
explains, or at any rate throws some light upon,
that most remarkable phenomenon, the existence
of slavery among ants. If you place a number of
larvae and pupae in front of a nest of the Horse
Ant, for instance, they are soon carried off; and
those which are not immediately required for food
remain alive for some time, and are even fed by
their captors.
3. Both the Horse Ant and the Slave Ant are
abundant species, and it must not unfrequently occur
that the former, being pressed for food, attack the
latter and carry off some of their larvae and pupae.
Under these circumstances it no doubt occasionally
happens that the pupae come to maturity in the
nests of the Horse Ant, and it is said that nests are
sometimes, though rarely, found in which, with the
legitimate owners, there are a few Formica fiisca.
With the Horse Ant this is, however, a very rare
An is.
33
and exceptional phenomenon; but with an aUicd
species, F. sanpdnea, a species which exists in some
of our southern counties and throughout Europe, it
has become an estabHshed habit. The F. sangumea
make periodical expeditions, attack neighbouring
nests, carrying off the larvae and pupae, selecting
those which will produce workers. When the latter
come to maturity they find themselves in a nest
consisting partly of F. sanguinea, partly of their
own species, the results of previous expeditions.
They adapt themselves to circumstances, assist in
the ordinary household duties, and, having no
young of their own species, feed and tend those of
the F. sangui7iea. But though the F. sanguinea
are thus aided by their slaves, or as they should
rather perhaps be called, by their auxiliaries, they
have not themselves lost the instinct of working.
It seems not improbable that there is some divi-
sion of functions between the two species, but we
have as yet no distinct knowledge on this point ;
and at any rate the F. sanguinea can " do " for
themselves and carry on a nest, if necessary, with-
out slaves.
4. Another species, the Amazon Ant {Polyergus
rufescens, fig. i), is much more dependent on its
slaves, being, indeed, almost entirely so.
For the knowledge of the existence of slavery
among ants we are indebted to Huber, and I can-
not resist quoting the passai^e in which he records
his discovery : —
34
Atits.
"On June 17, 1804," he says, "while walking in
the environs of Geneva between four and five in
the evening, I observed close at my feet, traversing
the road, a legion of Amazon Ants. They moved
in a body with considerable rapidity, and occupied
a space of from eight to ten inches in length by
three or four in breadth. In a few minutes they
quitted the road, passed a thick hedge, and entered
a pasture ground, where I followed them. They
wound along the grass without straggling, and
their column remained unbroken, notwithstanding
the obstacles they had to surmount. At length
they approached a nest inhabited by dark ash-
colour^d ants {Formica fusca, fig. 10), the dome of
which rose above the grass, at a distance of twenty
feet from the hedge. Some of its inhabitants were
guarding the entrance, but, on the discovery of an
approaching army, darted forth upon the advanced
guard. The alarm spread at the same moment in
the interior, and their companions came forth in
numbers from their underground residence. The
Amazon Ants, the bulk of whose army lay only at
the distance of two paces, quickened their march
to arrive at the foot of the ant-hill ; the whole bat-
talion, in an instant, fell upon and overthrew the
ash-coloured ants, who, after a short but obstinate
conflict, retired to the bottom of their nest. The
Amazon Ants now ascended the hillock, collected
in crowds on the summit, and took possession of
the principal avenues, leaving some of their com-
Ants.
35
panions to work an opening in the side of the ant-
hill with their teeth. Success crowned their enter-
prise, and by the newly-made breach the remainder
of the army entered. Their sojourn was, however,
of short duration, for in three or four minutes they
returned by the same apertures which gave them
entrance, each bearing off in its jaws a larva or a
pupa."
5. The expeditions generally start in the after-
noon, and are from 100 to 2,000 strong.
The Amazon Ant presents a striking lesson of the
degrading tendency of slavery, for these ants have
become entirely dependent on their slaves. Even
their bodily structure has undergone a change: the
mandibles have lost their teeth and have become
mere nippers, deadly weapons indeed, but useless
except in war. They have lost the greater part of
their instincts : their art— that is, the power of
building ; their domestic habits, for they show no
care for their own young, all this being done by the
slaves; their industry — for they take no part in
providing the daily supplies. If the colony changes
the situation of its nest the mistresses are all carried
by the slaves on their backs to the new one ; nay,
they have even lost the habit of feeding. Huber
placed 30 of them with some larvae and pupae and
a supply of honey in a box. "At first," he says,
" they appeared to pay some little attention to the
larvae, they carried them here and there, but pre-
sently replaced them. More than one-half of the
D 2
36
Anis.
Amazons died of hunger in less than two days;
they had not even traced out a dweUing, and the
few ants still in existence were languid and with-
out strength. I commiserated their condition, and
gave them one of their black companions. This
individual, unassisted, established order, formed a
chamber in the earth, gathered together the larvae,
extricated several young ants that were ready to
quit the condition of pupae, and preserved the life
of the remaining Amazons."
6. This obsei-vation has been fully confirmed by
other naturalists. However small the prison, how-
ever large the quantity of food, these stupid crea-
tures will starve in the midst of plenty rather than
feed themselves.
M. Forel was kind enough to send me a nest of
the Amazon Ants, and I kept it under observation
for more than four years. My specimens certainly
never fed themselves, and when the community
changed its nest, which they did several times, the
mistresses were carried from the one to the other
by the slaves. I was even able to observe one of
their marauding expeditions, in which, however,
the slaves took a part.
7. I do not doubt that, as Huber tells us, speci-
mens if kept by themselves in a box would soon die
of starvation, even if supplied with food. I have,
however, kept isolated specimens for three months
by giving them a slave for an hour or two a day to
clean and feed them : under these circumstances
Ants.
37
they remained in perfect health, while but for the
slaves they would have perished in two or three
days. Except the slave-making ants, and some of
the beetles which live with ants, I know no case
in nature of an animal having lost the instinct of
feeding.
8. In the Amazon Ants, the so-called workers,
though thus helpless and idle, are numerous, ener-
getic, and in some respects even brilliant. In another
slave-making ant, Strongylognathus, the workers are
much less numerous and so weak that it is an un-
solved problem how they contrive to make slaves.
In the genus Strong}' lognathus there are two
species, wS". huberi and 6". testaceiis. S. /mberi, which
was discovered by Forel, very much resembles
Polyergns rufescens in habits. They have sabre-
like mandibles, like those of Polyergns, and their
mode of fighting is similar, but they are much
weaker insects ; they make slaves of Tetrmnorium
ccespit2C7n, which they carry off as pupae. In attack-
ing the Tetraniorinms they seize them by the head
with their jaws just in the same way as Polyergns,
but have not strength enough to pierce them as the
latter do. Nevertheless, the Tetramoriums seem
much afraid of them.
9. The other species, Strongylognathus testaceus,
is even weaker than 5. hnberi, and their mode of life
is still in many respects an enigma. They also
keep the workers of Tetramorium in, so to say, a
state of slavery, but how they procure the slaves is
38
Ants.
still a mystery. They fight in the same manner
as Polyergiis; but are no match for the Tetra-
moriums, a courageous species, and one which lives
in large communities. On one occasion Forel
brought a nest of Tetraniorium and put it down
very near one of Strongylognathus testaceus with
Tetrainorium slaves. A battle at once commenced
between the two communities. The Strongylog-
nathus rushed boldly to the fight, but, though their
side won the day, this was mainly due to the slaves.
The Strongylognathus themselves were almost all
killed ; and though the energy of their attack
seemed at first to disconcert their opponents, Forel
assures us that they did not succeed in killing
even a single Tetraniorium. In fact, as he graphi-
cally observes, Strongylognathus is " a melancholy
caricature " of Polyergus, and it seems almost
impossible that by themselves they could success-
fully attack a nest of Tetj'amoriuni. Moreover, in
Strongylognathus, the workers are comparatively
few. Nevertheless, they are always found with the
Tetramoriums, and in these mixed nests there are
no males or females of Tetramorutm, but only
those of Strongylognathus. Again, the whole work
of the nest is done by the slaves, though Strongy-
lognat/ms has not, like Polyergus, entirely lost the
power of feeding itself
10. But if the economy of Strongylognathus is an
enigma, that of Anergates is still more mysterious.
It seems quite clear that Anergates cannot procure
Ants.
39
its slaves, if such they are, by marauding expeditions
Hke those of Polyergtis; in the first place, because
the Anergates are too few, and secondly, because
they are too weak. The whole question is rendered
more difficult because no larvae or pupas of Tetra-
mormm have ever been found in the mixed nests.
The community consisted of males and females of
Anergates, accompanied and tended by workers of
Tetramormm ccespitiiin. The Anergates are abso-
lutely dependent upon their slaves, and cannot
even feed themselves. The whole problem is,
therefore, most puzzhng and interesting.
11. These four genera offer us every gradation
from lawless violence to contemptible parasitism.
Formica sanguinea, which may be assumed to have
comparatively recently taken to slave-making, has
not as yet been materially affected.
The Amazon Ant {Polyergics), on the contrary,
already illustrates the lowering tendency of slavery.
They have lost their knowledge of art, their natural
affection for their young, and even their instinct
of feeding ! They are, however, bold and powerful
marauders.
In Strongylognathus, the enervating influence o
slavery has gone further, and told even on the bodily
strength. They are no longer able to capture their
slaves in fair and open warfare. Still they retain a
semblance of authority, and, when roused, will fight
bravely, though in vain.
12. In Anergates, finally, we come to the last scene
40
A nts.
of this sad history. We may safely conclude that
in distant times their ancestors lived, as so many
ants do now, partly by hunting, partly on honey;
that by degrees they became bold marauders, and
gradually took to keeping slaves ; that for a time
they maintained their strength and agility, though
losing by degrees their real independence, their arts,
and even many of their instincts ; that gradually
even their bodily force dwindled away under the
enervating influence to which they had subjected
themselves, until they sank to their present degraded
condition — weak in body and mind, few in numbers,
and apparently nearly extinct, the miserable repre-
sentatives of far superior ancestors, maintaining a
precarious existence as contemptible parasites of
their former slaves.
13. But putting these slave-making ants on one
side, we find in the different species of ants different
conditions of life, curiously answering to the earlier
stages of human progress. For instance, some
species, such as Formica fusca, live principally on
the produce of the chase ; for though they feed
partly on the honey-dew of aphides, they have not
domesticated these insects. These ants probably
retain the habits once common to all ants. They re-
semble the lower races of men, who subsist mainly
by hunting. Like them they frequent woods and
wilds, live in comparatively small communities, and
the instincts of collective action are but little de-
veloped among them. They hunt singly, and their
Ants.
41
battles are single combats, like those of the Homeric
heroes. Such species as the yellow Meadow Ant
represent a distinctly higher type of social life ; they
show more skill in architecture, may literally be said
to have domesticated certain species of aphides, and
their condition may be compared to the pastoral
stage of human progress — to the races which live
on the produce of their flocks and herds. Their
communities are more numerous ; they act much
more in concert ; their battles are not mere single
combats, for they know how to act in combination.
I am disposed to hazard the conjecture that they
will gradually exterminate the mere hunting species,
just as savages disappear before more advanced
races. Lastly, the agricultural nations may be
compared with the harvesting ants.
Thus there seem to be three principal types, offer-
ing a curious analogy to the three great phases— the
hunting, pastoral, and agricultural stages — in the
history of human development.
42
A fits.
VI.
1. The behaviour of ants to one another differs
much according to circumstances ; whether, for in-
stance, they are alone, or supported by friends. An
ant which would run away in the first case will de-
fend herself bravely in the second.
On one occasion several ants belonging to one of
my nests were feeding on some honey spread on a
slip of glass. One of them had got thoroughly
entangled in it. I took her and put her down
just in front of another individual belonging to the
same nest, and close by I placed a drop of honey.
The ant devoted herself to the honey and entirely
neglected her friend, whom she left to perish.
I then chloroformed one, and put her on the board
among her friends. Several touched her, but from
12 to 2.30 P.M. none took any particular notice of
her.
2. On the other hand, I have only on one occasion
seen a living ant expelled from her nest. I observed
(April 23, 1880) an ant carrying another belonging
to the same community away from the nest. The
condemned ant made a very feeble resistance. The
first ant carried her burthen hither and thither for
some time, evidently trying to get away from the
nest, which was enclosed by a barrier of fur. After
Ants.
43
watching for some time I provided the ant with
a paper bridge, up which she immediately went,
dropped her victim on the far side, and returned
home. Could this have been a case in which an
aged or invalid ant was being expelled from the
nest ?
3. In order to test the affection of ants belonging
to the same nest for one another, I tried the follow-
ing experiments. I took six ants from one of my
nests, imprisoned them in a small bottle, one end
of which was covered with a layer of muslin. I
then put the muslin close to the door of the nest.
The muslin was of open texture, the meshes, how-
ever, being sufficiently small to prevent the ants
from escaping. They could, however, not only see
one another, but communicate freely with their
antenns. We now watched to see whether the
prisoners would be tended or fed by their friends.
We could not, however, observe that the least notice
was taken of them. The experiment, nevertheless,
was less conclusive than could be wished, because
they might have been fed at night or at some time
when we were not looking. It struck me, there-
fore, that it would be interesting to treat some
strangers also in the same manner.
4- On September 2, therefore, I put two ants from
one of my nests into a bottle, the end of which was
tied up with muslin as described, and laid it down
close to the nest. In a second bottle I put two
ants from another nest of the same species. The
44
Ants.
ants which were at liberty took no notice of the
bottle containing their imprisoned friends. The
strangers in the other bottle, on the contrary, ex-
cited them considerably. The whole day one,
two, or more ants stood sentry, as it were, over the
bottle. In the evening no less than twelve were
collected round it, a larger number than usually
came out of the nest at any one time. The whole
of the next two days, in the same way, there
were several ants round the bottle containing the
strangers ; while, as far as we could see, no notice
whatever was taken of the friends. On the 9th
the ants had eaten through the muslin, and effected
an entrance. We did not chance to be on the
spot at the moment ; but as I found two ants lying
dead, one in the bottle and one just outside, I think
there can be no doubt that the strangers were
put to death. The friends throughout were quite
neglected.
5. In one of my nests was an ant which had come
into the world without antennae. Never having
previously met A'ith such a case, I watched her
with great interest ; but she never appeared to leave
the nest. At length one day I found her wander-
ing about in an aimless sort of manner, and
apparently not knowing her way at all. After a
while she fell in with some specimens of the little
yellow ant, who directly attacked her. I at once
set myself to separate them ; but owing either
to the wounds she had received from her enemies
Ants.
45
or to my rough though well-meant handling, or to
both, she was evidently much wounded, and lay
helplessly on the ground. After some time another
ant from her nest came by. She examined the
poor sufferer carefully, then picked her up gently
and carried her away into the nest. It would have
been difficult for any one who witnessed this scene
to have denied to this ant the possession of humane
feelings.
6. Again, on another occasion, I perceived a poor
ant lying on her back and quite unable to move. The
legs were in cramped attitudes, and the two antennas
rolled up in spirals. She was, of course, altogether
unable to feed herself After this I kept my eye
on her. Several times I tried uncovering the part
of the nest where she was. The other ants soon
carried her into the shaded part. One day the
ants were all out of the nest, probably for fresh air,
and had collected together in a corner of the box ;
they had not, however, forgotten her, but had
carried her with them. I took off the glass lid of
the box, and after a while they returned as usual
to the nest, taking her in again. The next day she
was still alive, but shortly afterwards, notwithstand-
ing all their care, she died.
At the present time I have two other ants per-
fectly crippled in a similar manner, so that they are
quite unable to move, but they have been tended
and fed by their companions, the one for five the
other for four months.
46
Ants.
7. In May, 1879, I gave a lecture on ants at the
Royal Institution, and was anxious to exhibit a
nest of the little yellow ant with the queen. While
preparing the nest, on May 9, we accidentally
crushed the queen. The ants, however, did no't
desert her, or drag her out as they do dead workers,
but, on the contrary, carried her with them into the
new nest, and subsequently into a larger one with
which I supplied them, congregating round her,
just as if she had been alive, for more than six
weeks, when we lost sight of her.
8. In order to ascertain whether ants knew their
tellows by any sign or pass-word, as has been
suggested in the case of bees, I was anxious to see
if they could recognise them when in a state of
insensibility. I tried, therefore, the following ex-
periments with some specimens of the little yellow
ant : —
September 10, at 6 P.M., a number of these ants
were out feeding on some honey, placed on one of
my tables, and surrounded by a moat of water. I
then took several ants, some belonging to the same
nest and some from another, and intoxicated them.
To do this I was obliged to put them for a few
moments in spirit, for no ant would voluntarily
drink more than was good for it. The sober ants
took them up one by one. Their own friends they
carried into the nest, while they threw the strangers
into the ditch.
9. It seems clear, therefore, that even in a condi-
Anis.
47
tion of insensibility ants are recognised by their
friends.
It has been already shown that with ants, as
with bees, while the utmost harmony reigns between
those belonging to the same community, all others
are enemies. I have elsewhere given ample proof
that a strange ant is never tolerated in a com-
munity. This of course implies that all the bees or
ants of a community have the power of recognising
one another — a most surprising fact, when we con-
sider their immense numbers. It is calculated that
in a single hive there may be as many as 50,000
bees, and in the case of ants the numbers are 'still
greater. In the large communities of ants it is
probable that there may be as many as from
400,000 to 500,000 ants, and in other cases even
these large numbers are exceeded.
10. If, however, a stranger is put among the ants
of another nest she is at once attacked.
Moreover, we have not only to deal with the fact
that ants know all their comrades, but that they
recognise them even after a lengthened separation.
Huber mentions some ants which he had kept
m captivity, and which had accidentally escaped
" met and recognised their former companions, fel!
to mutual caresses with their antenna, took them
up by their mandibles, and led them to their own
nests ; they came presently in a crowd to seek the
fugitives under and about the artificial ant-hill and
even ventured to reach the bell-glass, where 'they
48
A nts.
effected a complete desertion by carrying away
successively all the ants they found there. In a
few days the nest was depopulated. These ants
had remained four months without any communi-
cation."
Forel, indeed, regards the movements observed
by Huber as having indicated fear and surprise
rather than affection ; though he is quite disposed
to believe, from his own observations, that ants
would recognise one another after a separation of
several months.
1 1. The above observation recorded by Huber was
made casually, and he did not take any steps to test
it by subsequent experiments. The fact, however,
is of so much importance that I determined to make
further observations on the subject. In the first
place, I may repeat that I have satisfied myself by
many experiments, that ants from one community
introduced into another, — always, be it understood,
of the same species, — are attacked, and either
driven out or killed. It follows, therefore, that as
within the nest the most complete harmony pre-
vails—indeed, I have never seen a quarrel between
sister ants — they must by some means recognise
one another.
When we consider their immense numbers this
is sufficiently surprising; but that they should
recognise one another, as stated by Huber, after a
separation of months, is still more astonishing.
I determined therefore to repeat and extend his
observarions.
Anis.
49
VII.
1. Accordingly, on August 20, 1875, I divided a
colony of ants, so that one half were in one nest,
A, and the other half in another, B, and were kept
entirely apart.
On October 3, I put into nest B a stranger and
an old companion from nest A. They were marked
with a spot of colour. One of the ants imme-
diately flew at the stranger ; of the friend they took
no notice.
This experiment I repeated many times, and
always with the same result.
2. I separated one of my colonies of ants into two
halves on August 4, 1875, and kept them entirely
apart. From time to time I put specimens from
the one half back into the other. At first the
friends were always amicably received, but after
some months' separation they were occasionally
attacked, as if some of the ants, perhaps the
young ones, did not recognise them. Still they
were never killed, or driven out of the nest, so that
evidently when a mistake was made, it was soon
recognised. No one who saw the different manner
in which these ants and strangers were treated
could have the slightest doubt that the former were
recognised as friends and the latter as enemies
E
50
Anis.
The last three were put back on May 14, 1877,
that is^ to say, after a separation of a year and nine
months, and yet they were amicably received, and
evidently recognised as friends !
That ants and bees have a certain power of com-
munication cannot be denied, but how far their
powers reach is very doubtful.
3. Every one knows that if an ant or a bee in the
course of her rambles has found a supply- of food,
a number of others will soon make their way to
the store. This, however, does not necessarily
imply any power of describing localities. A very
simple sign would suffice, and very little intelli-
gence is implied, if the other ants merely accom-
pany their friend to the treasure which she has
discovered. On the other hand, if the ant or bee
can describe the locality, and send her friends to
the food, the case is very different. This point,
therefore, seemed to me very important; and I
have made a number of observations bearing on it.
4. The following may be taken as a type of what
happens under such circumstances. On June 12,
1874, I put an ant, belonging to a nest which I
had kept two or three days without food, to some
honey. She fed as usual, and then was returning
to the nest, when she met some friends, whom she
proceeded to feed. When she had thus distributed
her stores, she returned alone to the honey, none
of the rest coming with her. When she had a
second time laid in a stock of food, she again in
Aiits.
51
the same way fed several ants on her way towards
the nest; but this time five of those so fed returned
with her to the honey. In due course these five
would no doubt have brought others, and so the
number at the honey would have increased.
5. Again, one rather cold day, when but few ants
were out, I selected a specimen of an ant, belong-
ing to a nest which I had brought back with me from
Algeria. She was out hunting about 6 feet from
home, and I placed before her a large dead blue-
bottle fly, which she at once began to drag to the
nest. I then pinned the fly to a piece of cork, in a
small box, so that no ant could see the fly until
she had climbed up the side of the box. The ant
struggled, of course in vain, to move the fly. She
pulled first in one direction and then in another,
but, finding her efforts fruitless, she at length
started off back to the nest empty-handed. At
this time there were no ants coming out of the
nest. Probably there were some few others out
hunting, but for at least a quarter of an hour no
ant had left the nest. My ant entered the nest,
but did not remain there; in less than a minute
she emerged accompanied by seven friends. I
never saw so many come out of that nest together
before. In her excitement the first ant soon dis-
tanced her companions, who took the matter much
more coolly, and had all the appearance of having
come out reluctantly, or as if they had been asleep
and were only half awake. The first ant ran on
E 2
52
Ants.
ahead, going straight to the fly. The others fol-
lowed slowly and with many meanderings ; so
slowly, indeed, that for 20 minutes the first ant
was alone at the fly, trying in every way to move
it. Finding this still impossible, she again returned
to the nest, not chancing to meet any of her friends
by the way. Again she emerged in less than a
minute with eight friends, and hurried on to the fly.
They were even less energetic than the first party ;
and when they found they had lost sight of their
guide, they one and all returned to the nest. In
the meantime several of the first detachment had
found the fly, and one of them succeeded in de-
taching a leg, with which she returned in triumph
to the nest, coming out again directly with four or
five companions. These latter, with one exception,
soon gave up the chase and returned to the nest.
I do not think so much of this last case, because
as the ant carried in a substantial piece of booty in
the shape of the fly's leg, it is not surprising that
some of her friends should have accompanied her
on her return ; but surely the other two cases
indicate a distinct power of communication.
6. Lest, however, it should be supposed that the
result was accidental, I determined to try it again.
Accordingly on the following day I put another
large dead fly before an ant belonging to the same
nest, pinning it to a piece of cork as before. After
trying in vain for ten minutes to move the fly, my
ant started off" home. At that time I could only
Anis.
53
see two other ants of that species outside the nest.
Yet in a few seconds, considerably less than a
minute, she emerged with no less than 12 friends.
As in the previous case, she ran on ahead, and they
followed very slowly and by no means directly,
taking, in fact, nearly half an hour to reach the fly.
The first ant, after vainly labouring for about a
quarter of an hour to move the fly, started off"
again to the nest. Meeting one of her friends on
the way she conversed with her a little, then con-
tinued towards the nest, but, after going about a
foot, changed her mind, and returned with her
friend to the fly. After some minutes, during
which two or three other ants came up, one cf
them detached a leg, which she carried off to the
nest, coming out again almost immediately with
six friends, one of whom, curiously enough, seemed
to lead the way, tracing it, I presume, by scent. I
then removed the pin, and they carried off the fly
in triumph.
7. These experiments certainly seem to indicate
the possession by ants of something approaching to
language. It is impossible to doubt that the friends
were brought out by the first ant ; and as she re-
turned empty-handed to the nest, the others cannot
have been induced to follow her merely by observing
her proceedings.
Ants, like many other insects, possess two kinds
of eyes : a large compound eye on each side of the
head, and three small ones, which are called "ocelli,"
54
Ajits.
arranged in a triangle on the forehead. Wc do not
yet know how these eyes see, or whether the eyes
and ocelli act in the same way.
But it seems clear that the image produced by
the ocelli must be altogether different from the
picture given by the compound eyes ; and we may
therefore reasonably conclude that the two organs
have distinct functions.
8. The ocelli, or simple eyes, probably see in the
same manner as ours do. That is to say, the lens
throws an image on the back of the eye, which we
call the retina. In that case they would see every-
thing reversed, as we ourselves really do; though
long practice has given us the right impression.
The simple eye of insects thus resembles ours in
this respect.
As regards the mode of vision of the compound
eyes, there are two distinct theories. According to
one, each facet takes in only a small portion of the
field ; while, according to the other, each facet acts
as a separate eye.
9. This latter view has been maintained by many
high authorities, but it is difficult to understand
how so many images could be combined into one
picture. Some insects have more than 20,000 facets
on each side of their head. No ants, indeed, have
so many, but in some there are not less than 1,000.
In fact, these, so far fortunate, insects realise the
epigram of Plato —
Ants.
55
Thou lookest on the stars, my love,
Ah, would that I could be
Yon starry skies, with thousand eyes
That I might look on thee !
But if an ant sees 1,000 queens at once, when
only one is really present, this would seem to be a
bewildering privilege, and the prevailing opinion
among entomologists is, as already mentioned, that
each facet only takes in a portion of the object.
10. But while it is difficult to understand how
ants see, it is clear that they do see.
There could of course be little, if any, doubt, that
bees are capable of distinguishing colours; and I
have proved experimentally that this is the case.
Many eminent observers have regarded the an-
tennae of insects as auditory organs, and have
brought forward strong evidence in favour of their
view.
I have myself made experiments on grass-
hoppers, which convinced me that their antennae
serve as organs of hearing.
11. So far, however, as ants, bees, and wasps are
concerned, the evidence is very conflicting.
I have never succeeded in satisfying myself that
my ants, bees, or wasps heard any of the sounds
with which I tried them. I have over and over
again tested them with the loudest and shrillest
noises I could make, using a penny pipe, a dog-
whistle, a violin, as well as the most piercing and
startling sounds I could produce with my own voice,
but all without effect. At the same time, I care-
56
An is.
fully avoided inferring from this that they are really
deaf, though it certainly seems that their ran-e of
heanng is very different from ours.
12. In order, if possible, to throw some light upon
this interesting question, I made a variety of loud
noises, including those produced by a complete set
of tuning-forks, as near as possible to the ants
while they were bringing food into the nest In
these cases the ants were moving steadily and
in a most business-like manner, and any start
or alteration of pace would have been at once
apparent. I was never able, however, to perceive
that they took the slightest notice of any of these
sounds. Thinking, however, that they might, per-
haps, be too much absorbed by the idea of the
larvffi to take any notice of my interruptions, I took
one or two ants at random and put them on a strip
of paper, the two ends of which were supported by
pins with their bases in water. The ants imprisoned
under these circumstances wandered slowly back-
wards and forwards along the paper. As they did
so, I tested them in the same manner as before, but
was unable to perceive that they took the slightest
notice of any sound which I was able to produce.
I then took an ant belonging to one of the largest
European species, and tethered her on a board to
a pin by a delicate silk thread about 6 inches in
length. After wandering about for a while, she
stood still, and I then tried her in the same way;
but, like the other ant.s, she took no notice whatever
of the sounds.
Ants.
57
It is of course possible, if not probable, that ants,
even if deaf to sounds which we hear, may hear
others to which we are deaf
13. Having failed, therefore, in hearing them or
making them hear me, I endeavoured to ascertain
whether they could hear one another, but I was
not able to do so.
It is, however, far from improbable that ants
may produce sounds entirely beyond our range of
hearing. Indeed, it is not impossible that insects
may possess senses, or sensations, of which we can
no more form an idea than we should have been
able to conceive red or green if the human race
had been blind. The human ear is sensitive to
vibration, reaching at the outside to 38,000 in a
second. The sensation of red is produced when
470 millions of millions of vibrations enter the eye
in a similar time ; but between these two numbers
vibrations produce on us only the sensation of heat
—we have no special organs of sense adapted to
them. There is, however, no reason in the nature
of things why this should be the case with other
animals; and the problematical organs possessed
by many of the lower forms may have relation to
sensations which we do not perceive. If any appa-
ratus could be devised by which the number of
vibrations produced by any given cause could be
lowered so as to be brought within the range of
our ears, it is probable that the result would be
most interesting.
58
Ants.
VIII.
I. I have made a number of experiments on the
power of smell possessed by ants. I dipped
camel's-hair brushes into peppermint-water, essence
of cloves, lavender-water, and other strong scents,
and suspended them about a quarter of an inch
above the strips of paper along which the ants were
passing in the experiments above recorded. Under
these circumstances, while some of the ants passed
on without taking any notice, others stopped when
they came close to the pencil, and, evidently per-
ceiving the smell, turned back. Soon, however,
they returned and passed the scented pencil. After
doing this two or three times they generally took
no further notice of the scent. This experiment
left no doubt on my mind ; still, to make the matter
even more clear, I experimented with ants placed
on an isolated strip of paper. Over the paper, and
at such a distance as almost, but not quite, to touch
any ant which passed under it, I again suspended
a camel's-hair brush, dipped in assafoetida, lavender-
water, peppermint-water, essence of cloves, and
other scents. In these experiments the results were
very marked ; and no one who watched the
behaviour of the ants under these circumstances
Ants.
59
could have the sHghtest doubt as to their power of
smell.
2. I then took a large queen ant and tethered her
on a board by a thread. When she was quite quiet
I tried her with the tuning-forks, but they did not
disturb her in the least. I then approached the
feather of a pen very quietly, so as almost to touch
first one and then the other of the antennae, which,
however, did not move. I then dipped the pen in
essence of musk, and did the same : the antenna
was slowly retracted and drawn quite back. I then
repeated the same with the other antenna. If I
touched the antenna, the ant started away appa-
rently smarting. I repeated the same with essence
of lavender, and with a second ant. The result was
the same.
Many of my other experiments point to the same
conclusion ; and, in fact, there can be no doubt
whatever that in ants the sense of smell is highly
developed.
3. In order to test the intelligence of ants, it has
always seemed to me that there was no better way
than to ascertain some object which they would
clearly desire, and then to interpose some obstacle
which a little ingenuity would enable them to over-
come. I therefore placed some larvee in a cup
which I put on a slip of glass surrounded by water,
but accessible to the ants by one pathway, in which
was a bridge consisting of a strip of paper two-
thirds of an inch long and one-third of an inch
6o
A7tis.
wide. Having then put a Black Ant from one of
my nests to these larvae, she began carrying them
off, and by degrees a number of friends came to
help her. I then, when about 25 ants were so
engaged, moved the little paper bridge slightly, so
as to leave a chasm just so wide that the ants could
not reach across. They came and tried hard to
do so ; but it did not occur to them to push the
paper bridge, though the distance was only about
one-third of an inch, and they might easily have
done so. After trying for about a quarter of an
hour they gave up the attempt, and returned home.
This I repeated several times.
4. Then, thinking that paper was a substance to
which they were not accustomed, I tried the same
with a bit of straw one inch long and one-eighth of
an inch wide. The result was the same. I repeated
this more than once.
Again, I suspended some honey over a nest of
Yellow Ants at a height of about half an inch, and
accessible only by a paper bridge more than 10 feet
long. Under the glass I then placed a small heap
of earth. The ants soon swarmed over the earth
on to the glass, and began feeding on the honey. I
then removed a little of the earth, so that there was
an intei-val of about one-third of an inch between
the glass and the earth ; but, though the distance
was so small, they would not jump down, but pre-
ferred to go round by the long bridge. They tried
in vain to stretch up from the earth to the glas.s.
A?ils.
6i
which, however, was just out of their reach, though
they could touch it with their antennae ; but it did
not occur to them to heap the earth up a little,
though if they had moved only half a dozen par-
ticles of earth they would have secured for them-
selves direct access to the food. At length they
gave up all attempts to reach up to the glass, and
went round by the paper bridge. I left the arrange-
ment for several weeks, but they continued to go
round by the long paper bridge.
5. Again I varied the experiment as follows: —
Having left a nest without food for a short time, I
placed some honey on a small wooden brick sur-
rounded b}' a little moat of glycerine half an inch
wide and about one-tenth of an inch in depth.
Over this moat I then placed a paper bridge, one
end of which rested on some fine mould. I then
put an ant to the honey, and soon a little crowd
was collected round it. I then removed the paper
bridge : the ants could not cross the glycerine ;
they came to the edge and walked round and
round, but were unable to get across, nor did it
occur to them to make a bridge or bank across the
glycerine with the mould which I had placed so
conveniently for them. I was the more surprised
at this on account of the ingenuity with which they
avail themselves of earth for constructing their
nests. For instance, wishing, if possible, to avoid
the trouble of frequently moistening the earth in
my nests, I supplied one of my communities with a
62
Ants.
frame containing, instead of earth, a piece of linen,
one portion of which projected beyond the frame
and was immersed in water. The Hnen then
sucked up the water by capillary attraction, and
thus the air in the frame was kept moist. The ants
approved of this arrangement, and took up their
quarters in the frame. To minimize evaporation I
usually closed the frames all round, leaving only
one or two small openings for the ants, but in this
case I left the outer side of the frame open. The
ants, however, did not like being thus exposed ;
they, therefore, brought earth from some little
distance, and built up a regular wall along the open
side, blocking up the space between the upper and
lower plates of glass, and leaving only one or two
small openings for themselves. This struck me as
very ingenious. The same expedient was, more-
over, repeated under similar circumstances by the
slaves belonging to my nest of Amazon Ants.
63
SECTION II.— BEES AND WASPS.
I.
I. Originally I had intended to make my
experiments principally with bees, but soon found
that ants were on the whole more suitable for my
purpose.
In the first place, ants are much less excitable,
they are less liable to accidents, and from the ab-
sence of wings are more easy to keep under con-
tinuous observation.
Still, I have made a certain number of obser-
vations with bees, some of which may be worth
recording here.
As already mentioned, the current statements
with reference to the language of social insects
depend much on the fact that when one of them,
either by accident or in the course of its rambles,
has discovered a stock of food, in a very short time
many others arrive to profit by the discovery. This,
however, does not necessarily imply any power of
describing localities. If the bees or ants merely
follow their more fortunate comrade, the matter is
comparatively simple ; if, on the contrary, others
are sent, the case becomes very different.
64
Bees and Wasps.
2. In order to test this I proposed to keep honey
in a given place for some time, so as to satisfy my-
self that it would not readily be found by the bees ;
and then, after bringing a bee to the honey, to
watch whether it brought others, or sent them— the
latter, of course, implying a much higher order of
intelligence and power of communication.
I never, however, could satisfy myself that bees
which had found a store of honey sent others to it :
the rest, if they came at all, were, as far as I could
ascertain, always brought.
3. The result of my experiments on the hearing- of
bees has surprised me very much. It is generally
considered that to a certain extent the emotions of
bees are expressed by the sounds they make, which
seems to imply that they possess the power of
hearing. I do not by any means intend to deny
that this is the case. Nevertheless, I never found
them take any notice of any noise which I made,
even when it was close to them. I tried one of my
bees with a violin. I made all the noise I could,
but to my surprise she took no notice. I could
not even see a twitch of the antennae. The next
day I tried the same with another bee, but could
not see the slightest sign that she was conscious
of the noise. I have tried several bees with a dog-
whistle and a shrill pipe ; but they took no notice
whatever, nor did a set of tuning-forks, which I
tried on a subsequent day, have any more effect.
These tuning-forks extended over three octaves,
Bees and Wasps.
65
beginning with a below the ledger line. I also
tried with my voice, shouting, &c., close to the head
of a bee ; but, in spite of my utmost efforts, the
bees took no notice. I repeated these experiments
at night, when the bees were quiet ; but no noise
that I could make seemed to disturb them in the
least.
4. The consideration of the causes which have led
to the structure and colouring of flowers is one of
the most fascinating parts of natural history. Most
botanists are now agreed that insects, and especially
bees, have played a veiy important part in the
development of flowers. While in many plants,
almost invariably with inconspicuous blossoms, the
pollen is carried from flower to flower by the wind,
in the case of almost all large and brightly coloured
flowers this is effected by the agency of insects. In
such flowers the colours, scent, and honey serve to
attract insects, while the size and form are arranged
in such a manner that the insects fertilise them with
pollen brought from another plant.
5. There could, therefore, be little doubt that bees
possess a sense of colour. Nevertheless, I thought
it would be desirable to prove this, if possible, by
actual experiment, which had not yet been done.
Accordingly, on July 12, I brought a bee to some
honey which I had placed on blue paper, and about
3 feet off I placed a similar quantity of honey on
orange paper. After she had returned twice I trans-
posed the papers ; but she returned to the honey on
F
66
Bees and Wasps.
the blue paper. After she had made three more
visits, always to the blue paper, I transposed them
again, and she again followed the colour, though
the honey was left in the same place. The follow-
ing day I was not able to watch her ; but on the
14th at —
7.29 A.M. she returned to the honey")
on the blue paper . . J At 7.31 she left.
7-34 „ „ „ 7.41
I then again transposed the papers. At 8.5 she
returned to the old place, and was just going to
alight ; but observing the change of colours, without
a moment's hesitation darted off to the blue. No
one who saw her at that moment could have enter-
tained the slighest doubt that she perceived the
difference between the two colours.
6. On October 2 I placed some honey on slips of
glass resting on black, white, yellow, orange, green,
blue, and red paper. A bee which was placed on
the orange returned twenty times to that slip of
glass, only once or twice visiting the others, though
I moved the position and also the honey. The next
morning again two or three bees paid twenty-one
visits to the orange and yellow, and only four to all
the other slips of glass. I then moved the glass,
after which, out of thirty-two visits, twenty-two
were to the orange and yellow. This was due, I
believe, to the bee having been placed on the
Bees and Wasps.
67
orange at the beginning of the experiment. I do
not attribute it to any preference for the orange or
yellow; indeed, I shall presently give reasons for
considering that blue is the favourite colour of bees.
7. I had ranged my colours in a line, with the blue
at one end. It was a cold morning, and only one
bee came. She had been several times the pre-
ceding day, generally to the honey which was on
the blue paper. This day also she came to the
blue ; I moved the blue gradually along the line
one stage every half-hour, during which time she
paid fifteen visits to the honey, in every case going
to that which was on the blue paper.
These experiments only prove that bees have
the power of distinguishing one colour from
another. I afterwards, however, made a second
series of experiments which indicated that they
prefer blue to either red, white, yellow, or green.
68
Bees and Wasps.
n.
1. I have been much struck by the industry of
wasps. They commence work early in the morn-
ing, and do not leave off till dusk. I have several
times watched a wasp the whole day, and from
morning to evening, if not disturbed, she worked
without any interval for rest or refreshment.
Being anxious to compare bees and wasps in this
respect, on August 6, 1882, I accustomed a wasp
and three bees to come to some honey put out for
them on two tables, one allotted to the wasp, the
other to the bees. The last bee came at 7.15 P.M.
The wasp continued working regularly till 7.47,
coming at intervals of between six and seven
minutes. Next morning, when I went into my
study a few minutes after 4 A.M., I found the wasp
already at the honey. The first bee came at 5.45,
the second at 6.
It would, however, perhaps be unfair to the bees
to regard this as indicating that they are less in-
dustrious than wasps. The deficiency may be due
to their being more susceptible to cold.
2. The wasp occupied about a minute, or even
less, in supplying herself with honey, and made
during the day no less than 116 visits to the store,
or 232 journeys between my room and her nest,
Bees and Wasps.
69
durine which she carried off rather more than 64
grains of honey.
I may add that I then left home for a few days.
I covered over the honey, leaving only a small
entrance for the wasp. When I returned on the
1 2th, I found her still at work, and by herself It
was evident that she had continued her labours,
but without bringing any friends to assist her.
My wasps, though courageous, were always on the
alert, and easily startled. It was, for instance,
more difficult to paint them than the bees ; never-
theless, though I tried them with a set of tuning-
forks covering three octaves, with a shrill whistle, a
pipe, a violin, and my own voice, making in each
case the loudest and shrillest sounds in my power,
I could see no symptoms in any case that they
were conscious of the noise.
3. The following fact struck me as rather remark-
able. One of my wasps smeared her wings with
syrup, so that she could not fly. When this hap-
pened to a bee, it was only necessary to carry her to
the alighting-board of the hive, when she was soon
cleaned by her comrades. But I did not know
where this wasp's nest was, and therefore could not
pursue a similar course with her. At first, then, I
was afraid that she was doomed. I thought, how-
ever, that I would wash her, fully expecting, indeed,
to terrify her so much that she would not return
again. I caught her, put her in a bottle half full of
water, and shook her up well till the honey was
70
Bees and Wasps.
washed off. I then transferred her to another
bottle, and put her in the sun to dry. When she
appeared to have recovered I let her out : she at
once flew to her nest, and I never expected to see
her again. To my surprise, in 13 minutes she re-
turned as if nothing had happened, and continued
her visits to the honey all the afternoon.
4. This experiment interested me so much that
I repeated it with another marked wasp, this time,
however, keeping the wasp in the water till she was
quite motionless and insensible. When taken out
of the water she soon recovered ; I fed her ; she
went quietly away to her nest as usual, and re-
turned after the usual absence. The next morning
this wasp was the first to visit the honey.
I once kept a tame wasp for no less than nine
months.
I took her, with her nest, in the Pyrenees, early
in May. The nest consisted of about 20 cells, the
majority of which each contained an egg; but as
yet no grubs had been hatched out, and, of course,
my wasp was still alone in the world.
5. I had no difficulty in inducing her to feed on
my hand ; but at first she was shy and nervous. She
kept her sting in constant readiness ; and once or
twice in the train, when the railway officials came
for tickets, and I was compelled to hurry her back
into her bottle, she stung me slightly — I think,
however, entirely from fright.
Gradually she became quite used to me, and
Bees and Wasps.
71
when I took her on my hand apparently expected
to be fed. She even allowed me to stroke her
without any appearance of fear, and for some
months I never saw her sting.
When the cold weather came on she fell into a
drowsy state, and I began to hope she would
hibernate and survive the winter. I kept her in a
dark place, but watched her carefully, and fed her
if ever she seemed at all restless.
6. She came out occasionally, and seemed as well
as usual till near the end of February, when one
day I observed she had nearly lost the use of her
antennae, though the rest of the body was as usual.
She would take no food. Next day I tried again
to feed her ; but the head seemed dead, though she
could still move her legs, wings, and abdomen.
The following day I offered her food for the last
time ; but both head and thorax were dead or
paralysed ; she could but move her tail, a last
token, as I could almost fancy, of gratitude and
affection. As far as I could judge, her death was
quite painless ; and she now occupies a place in
the British Museum.
As regards colours, I satisfied myself that wasps
are capable of distinguishing colour, though they
do not seem so much guided by it as bees are.
7. One day, at 7 A.M., I marked a common
worker wasp ( Vespa vulgaris^, and placed her to
some honey on a piece of green paper 7 inches by
4|. She worked with great industry. After she
72
Btrs and Wasps.
had got well used to the green paper I moved it
1 8 inches off, putting some other honey on blue
paper where the green had previously been. She
returned to the blue. I then replaced the green
paper for an hour, during which she visited it
several times, after which I moved it i8 inches, as
before, and put brick -red paper in its place. She
returned to the brick-red paper. But although
this experiment indicates that this wasp was less
strongly affected by colours than the bees which I
had previously observed, still I satisfied myself that
she was not colour-blind.
8. I moved the green paper slightly and put the
honey, which, as before, was on a slip of plain glass,
about 4 feet off. She came back and lit on the
green paper, but finding no honey, rose again, and
hawked about in search of it. After 90 seconds I
put the green paper under the honey, and in 15
seconds she found it. Then, while she was absent
at the nest, I moved both the honey and the paper
about a foot from their previous positions, and
placed them about a foot apart. She returned as
usual, hovered over the paper, lit on it, rose again,
flew about for a few seconds, lit again on the paper,
and again rose. After two minutes had elapsed I
slipped the paper under the honey, when she almost
immediately (within five seconds) lit on it. It
seems obvious, therefore, that she could see green.
9. I then tried her with red. I placed the honey
on brick-red paper, and left her for an hour, from
Bees and Wasps.
73
5 P.M. to 6 P.M., to get accustomed to it. During
this time she continued her usual visits. I then
put the honey and the coloured paper about a foot
apart ; she returned first to the paper and then to
the honey. I then transposed the honey and the
paper. This seemed to puzzle her. She returned
to the paper, but did not settle. After she had
hawked about for lOO seconds I put the honey on
the red paper, when she settled on it at once. I
then put the paper and the honey again i8 inches
apart. As before, she returned first to the paper,
but almost immediately went to the honey. In a
similar manner I satisfied myself that she could see
yellow.
lo. Again, on August 1 8 I experimented on two
wasps, one of which had been coming more or less
regularly to some honey on yellow paper for four
days, the other for twelve — coming, that is to say,
for several days the whole day long, and on all the
others, with two or three exceptions, for at least
three hours in the day. Both, therefore, had got
well used to the yellow paper. I then put blue
paper where the yellow had been, and put the
yellow paper with some honey on it about a foot
off. Both the wasps returned to the honey on the
blue paper. I then moved both the papers about
a foot, but so that the blue was somewhat nearer
the original position. Both again returned to the
blue. I then transposed the colours, and they both
returned to the yellow.
74
SECTION III.— THE COLOURS OF
ANIMALS.
I.
I. There are few more interesting parts of natural
history than the study of the causes which have led
to the present colours of animals and plants. As
regards plants, and especially flowers, I shall have
something to say in a future chapter, and I will
now therefore confine myself to animals.
The colour of animals is by no means a matter
of chance ; it depends on many considerations, but
in the majority of cases tends to protect the animal
from danger by rendering it less conspicuous.
Perhaps it may be said that if colouring is mainly
protective, there ought to be but few brightly-
coloured animals. There are, however, not a few
cases in which vivid colours are themselves protec-
tive. The kingfisher itself, though so brightly
coloured, is by no means easy to see. The blue
harmonises with the water, and as it darts along
the stream it looks almost like a flash of sunlight ;
besides which, protection is not the only considera-
The Colours of Anivials.
75
tion. Let us now consider the prevalent colours of
animals and see how far they support the rule.
2. Desert animals, for instance, are generally the
colour of the desert. Thus, for instance, the lion,
the antelope, and the wild ass are all sand-coloured.
"Indeed," says Canon Tristram, "in the desert,
where neither trees, brushwood, nor even undula-
tion of the surface afford the slightest protection to
its foes, a modification of colour which shall be
assimilated to that of the surrounding country, is
absolutely necessary. Hence, without exception,
the upper plumage of every bird, whether lark,
chat, sylvain, or sand grouse, and also the fur of all
the smaller mammals and the skin of all the snakes
and lizards, is of one uniform sand colour."
It is interesting to note that, while the lion is sand-
coloured like the desert, the long, upright yellow
stripes of the tiger make it very difficult to see the
animal among the long dry grasses of the Indian
jungles in which it lives. The leopard, again, and
other tree cats are generally marked with spots
which resemble gleams of light glancing through
the leaves.
3. The colours of birds are in many cases perhaps
connected with the position and mode of construc-
tion of their nests. Thus, we know that hen birds
are generally less brightly coloured than the cocks,
and this is partly, perhaps, because bright colours
would be a danger to the hens while sitting on their
eggs. When the nest is placed underground or in
76
TJie Colours of A nivials.
the hole of a tree, &c., we find it no longer to be such
an invariable rule that the hen bird is dull-coloured ;
but, on the contrary, she is then often as gaily-
coloured as the male. Such, for instance, is the
case with the hen kingfisher, which is one of the
brightest of British birds and one of the very few
which make their nests underground ; the hen
woodpecker, which is also gaily-coloured and builds
in hollow trees, forms a second instance.
In the few cases where the hens are as con-
spicuously coloured as the cocks, and yet the nest
is open to view, we generally find that the hens
are strong, pugnacious birds, and well able to
defend themselves. There are even instances,
though these are comparatively rare, in which the
hens are more brilliantly-coloured than the cocks ;
and it is an interesting fact that it is then the cocks,
and not the hens, which hatch the eggs.
4. It therefore seems to be a rule, with very few
exceptions, that when both the cocks and hens are
of strikingly gay or conspicuous colours, the nest
is such as to conceal the sitting bird ; while, when-
ever there is a striking contrast of colours, the nest
is open and the sitting bird exposed to view.
Again, most fishes are dark above and pale
below. This points to the same fact, for when one
looks down into the dark water, the dark colour of
their backs renders them the less easy to distin-
guish ; while, to an enemy looking up from below,
the pale belly would be less conspicuous against
The Colours of A niinals.
77
the light of the sky. Those fishes which live deep
down in the depths of the ocean present no such
contrast between the upper and under surface.
Many of the smaller animals which live in the sea
are as transparent as glass, and are consequently
very difficult to distinguish.
5. It is sometimes said that if animals were
really coloured with reference to concealment,
sheep would be green, like grass. This, however,
is quite a mistake. If they were green they would
really be more easy to see. In the grey of the morn-
ing and the evening twilight, just the time when wild
animals generally feed, grey and stone colours are
most difficult to distinguish. Sheep were originally
mountain animals, and everyone who has ever been
on a mountain-side knows how difficult it is to
distinguish a sheep, at some distance, from a mass
of stone or rock.
6. It is, again, a great advantage to the rabbit
and hare to be coloured like earth ; black or white
rabbits are more easy to see, and consequently
more likely to be killed. This, however, does not
apply to those which are kept in captivity, and we
know that tame rabbits are often black and white.
Again, in the far north, where for months together
the ground is covered with snow, the white colour,
which would be a danger here, becomes an advan-
tage ; and many arctic animals, like the polar bear
and polar hare, are white, while others, such as the
mountain hare and ptarmigan, change their
78
The Colours of Animals.
colour, being brown in summer and white in winter.
So are the arctic fox and the ermine, to whom it
IS then an advantage to be white, not to avoid
danger, but in order that they may be the more
easily able to steal unperceived upon their prey.
7. Many of the cases in which certain insects
escape danger by their similarity to plants are well
known; the leaf insect and the walking-stick
insect* are familiar and most remarkable cases.
The larvae of insects afford, also, many interesting
examples, and in other respects teach us, indeed,
many instructive lessons. It would be a great
mistake to regard them as merely preparatory
stages in the development of the perfect insect.
They are much more than this, for external circum-
stances act on the larvae, as well as on the perfect
insect : both, therefore, are liable to adaptation.
In fact, the modifications which insect larvae under-
go may be divided into two kinds — developmental,
or those which tend to approximation to the mature
form ; and adaptational or adaptive, those which
tend to suit them to their own mode of life.
8. It'is a remarkable fact, that the forms of larvae
do not depend on those of the mature insect. In
many cases, for instance, very similar larvae produce
extremely dissimilar insects. In other cases, similar,
or comparatively similar, perfect insects have very
* These are insects which inhabit warm regions, and they are so
called because they so strikingly resemble leaves, and bits of stick,
respectively.
The Colours of Animals.
79
dissimilar larvae. Indeed, a classification of insects
founded on larvae would be quite different from
that founded on the perfect insects. The group to
which the bees, wasps, and ants belong, for instance,
and which, so far as the perfect insects are con-
cerned, form a very natural division, would be
divided into two ; or rather one portion of them —
namely, the saw-flies — would be united to the but-
terflies and moths. Now, why do the larvae of
saw-flies differ from those of their allies, and re-
semble those of butterflies and moths .'' It is
because their habits differ from those of ants and
bees, and they feed on leaves like ordinary cater-
pillars.
9. In some cases the form changes considerably
during the larval, state. From this point of view,
the transformations of a small beetle, called Sitaris,
which have been carefully observed by M. Fabre,
are peculiarly interesting.
10. The genus Sitaris, which is allied to the
blister-fly and to the oil-beetle, is parasitic on a
kind of solitary bee which excavates subterranean
galleries, each leading to a cell. The eggs of the
beetle, which are deposited at the entrance of the
galleries made by the bees, are hatched at the end
of September or beginning of October, and we
might not unnaturally expect that the young larvae,
which are active little creatures with six serviceable
legs, would at once eat their way into the cells of
the bee. No such thing : till the month of April
8o
The Colours of Animals.
following they remain without leaving their birth-
place, and consequently without food ; nor do they
in this long time change either in form or size.
M. Fabre ascertained this, not only by examining
the burrow of the bees, but also by direct obser-
vations of some young larvae kept in captivity. In
April, however, his captives at last awoke from
their long lethargy, and hurried anxiously about
their prisons. Naturally inferring that they were
in search of food, M. Fabre supposed that this
would consist either of the larvae or pupae of the
bee, or of the honey with which it stores its cell.
All three were tried without success. The first
two were neglected ; and the larvae, when placed on
the latter, either hurried away or perished in the
attempt, being evidently unable to deal with the
sticky substance. M. Fabre was in despair. The
first ray of light came to him from our countryman
Newport, who ascertained that a small parasite
found on one of the wild bees was, in fact, the
larva of the oil-beetle. The larvae of Sitaris much
resembled this larva. Acting on this hint, M. Fabre
examined many specimens of the bee, and found
on them at last the larvae of his Sitaris. The
males of the bee emerge from the pupae sooner
than the females, and M. Fabre ascertained that, as
they come out of their galleries, the little Sitaris
larvae fasten upon them.. Not, however, for long :
instinct teaches them that they are not yet in the
straight path of development ; and, watching their
The Colours of A nivials.
81
opportunity, they pass from the male to the female
bee. Guided by these indications, M. Fabre exa-
mined several cells of the bee ; in some, the egg of
the bee floated by itself on the surface of the honey ;
in others, on the egg, as on a raft, sat the still more
minute larva of the Sitaris. The mystery was
solved. At the moment when the egg is laid, the
Sitaris larva springs upon it. Even while the poor
mother is carefully fastening up her cell, her mortal
enemy is beginning to devour her offspring ; for
the egg of the bee serves not only as a raft, but as
a repast. The honey, which is enough for either,
would be too little for both ; and the Sitaris, there-
fore, at its first meal, relieves itself from its only
rival. After eight days the egg is consumed, and
on the empty shell the Sitaris undergoes its first
transformation, and makes its appearance in a very
different form.
II. The honey, which was fatal before, is now
necessary — the activity, which before was necessary,
is now useless ; consequently, with the change of
skin, the active, slim larva changes into a white fleshy
grub, so organised as to float on the surface of the
honey, with the mouth beneath and the breathing-
holes above the surface ; for insects breathe, not as
we do through the mouth, but through a row of
holes arranged along the side. In this state it
remains until the honey is consumed ; then the
animal contract.s, and detaches itself from its skin,
within which the further transformations take place.
G
82
The Colours of Animals.
In the next stage the larva has a soHd corneous
envelope and an oval shape, and, in its colour, con-
sistency, and immobility, resembles the chrysalis of
a fly. The time passed in this condition varies
much. When it has elapsed, the animal moults
again, again changes its form ; after this, it be-
comes a pupa, without any remarkable peculiarities.
Finally, after these wonderful changes and adven-
tures, in the month of August the perfect beetle
makes its appearance.
The Colours of Animals.
83
II.
1. In fact, whenever in any group we find .differ-
ences in form or colour, we shall always find them
associated with differences in habit. Let us take the
case of Caterpillars. The prevailing colour of cater-
pillars is green, like that of leaves. The value of
this to the young insect, the protection it affords,
are obvious. We must all have observed how dif-
ficult it is to distinguish small green caterpillars
from the leaves on which they feed. When, how-
ever, they become somewhat larger, their form
betrays them, and it is important that there should
be certain marks to divert the eye from the outlines
of the body. This is effected, and much protec-
tion is given, by longitudinal lines (fig. 11), which
accordingly are found on a great many caterpillars.
These lines, both in colour and thickness, much
resemble some of the lines on leaves (especially
those, for instance, of grasses), and also the streaks
of shadow which occur among foliage. If, how-
ever, this be the explanation of them, then they
ought to be wanting, as a general rule, in very
small caterpillars, and should prevail most among
those which feed on or among grasses.
2. Now, similar lines occur on a great number of
caterpillars belonging to most different groups of
G 2
84
The Colours of Animals.
butterflies and moths, as you may sec by turning over
the illustrations of any monograph of the group.
They exist among the Hawk-moths — as, for in-
stance, in the Humming-bird Hawk-moth ; they
Pig. II.— The Caterpillar of the Marbled White
Butterfly {Arge galathed).
occur in many butterflies, especially in those which
feed on grass ; and in many moths. But you will
find that the smallest caterpillars rarely possess
these white streaks. As regards the second point,
The Colours of Animals. 85
also, the streaks are generally wanting in caterpillars
which feed on large-leaved plants. The Satyrido3,
on the contrary, all possess them, and all live on
grass. In fact we may say, as a general rule, that
these longitudinal streaks only occur on caterpillars
which live on or among narrow-leaved plants. As
the insect grows, these lines often disappear on
certain segments, and are replaced by diagonal
lines. These diagonal lines (fig. 12) occur in a
great many caterpillars, belonging to the most dis-
tinct families of butterflies and moths. They come
off just at the same angle as the ribs of leaves, and
resemble them very much in general effect. They
occur also especially on species which feed on
large-leaved plants ; and I believe I may say that
though a great many species of caterpillars present
these lines, they rarely, if ever, occur in species
which live on grass ; while, on the contrary, they
are very frequent in those species which live on
large-leaved plants.
3. It might at first be objected to this view that
there are many cases, as in the Elephant Hawk-
moth, in which caterpillars have both. A little
consideration, however, will explain this. In small
caterpillars these oblique lines would be useless,
because they must have some relation, not only
in colour, but in their distance apart, to the ribs
of the leaves. Hence, while there are a great
many species which have longitudinal lines when
young, and diagonal ongs when they are older
86
The Colours of Animals.
and larger, there is not, I believe, a single one
which begins with diagonal lines, and then replaces
them with longitudinal ones. The disappearance
of the longitudinal lines on those segments which
have diagonal ones, is striking, where the lines
are marked. It is an advantage, because white
lines crossing one another at such an angle have
no relation to anything which occurs in plants,
The Colours of Animals.
87
and would make the creature more conspicuous
When, therefore, the diagonal lines are developed,
the longitudinal ones often disappear. There is
one other point in connection with these diagonal
lines to which I must call your attention.
4. In many species they are white, but in some
cases— as, for instance, in the beautiful green cater-
pillar of the Privet Hawk-moth — the white streak
is accompanied by a coloured one, in that case lilac.
At first we might think that this would be a dis-
advantage, as tending to make the caterpillar more
conspicuous ; and in fact, if we put one in full view
— for instance, out on a table — and focus the eye
on it, the coloured lines are very striking. But we
must remember that the habit of the insect is to sit
on the lower side of the leaf, generally near the
middle rib, and in the subdued light of such a
situation, especially if the eye be not looking
exactly at them, the coloured lines beautifully
simulate a line of soft shadow, such as must always
accompany a strong rib ; and I need not tell any
artist that the shadows of yellowish-green must be
purplish. Moreover, any one who has ever found
one of these large caterpillars will, I am sure, agree
with me that it is surprising, when we consider
their size and conspicuous colouring, how difficult
it is to see them.
5. But though the prevailing colour of caterpillars
is green, there are numerous exceptions. In one
great family of moths the prevailing colour is brown.
88
The Colours of Animals.
These caterpillars, however, escape observation by
their great similarity to brown twigs — a resem-
blance which is heightened by their peculiar atti-
tudes, and in many cases by the existence of warts
or protuberances, which look like buds. Some,
however, even of these caterpillars, when very
young, are green. Again, some caterpillars are
white. These feed on and burrow in wood. The
Ringlet Butterfly also has whitish caterpillars, and
this may at first sight appear to contradict the rule,
since it feeds on grass. Its habit is, however, to
keep at the roots by day, and feed only at night.
6. In various genera we find Black caterpillars,
which are of. course very conspicuous, and, so far as
I know, not distasteful to birds. In such cases,
however, it will be found that they are covered
with hairs or spines, which protect them from most
birds. In these species the bold dark colour may
be an advantage, by rendering the hair more con-
spicuous. Many caterpillars are black and hairy,
but I do not know any large caterpillar which is
black and smooth.
7. Brown caterpillars, also, are frequently pro-
tected by hairs or spines in the same way ; but,
unlike black ones, they are frequently naked. These
fall into two principal categories : firstly, those
which, like the Geometridce, put themselves into
peculiar and stiff attitudes, so that in form, colour,
and position they closely resemble bits of dry stick ;
and, secondly, those which feed on low plants, con-
The Colours of Animals. 89
cealing themselves on the ground by day, and only
coming out in the dark.
Yellow and yellowish-green caterpillars are abun-
dant, and their colour is a protection. Red and
blue, on the contrary, are much less common
colours, and are generally present as spots.
8. Moreover, caterpillars with red lines or spots are
generally hairy, and this for the reason given above.
Such species, therefore, would be avoided by birds.
There are, no doubt, some apparent exceptions.
The Swallow-tail Butterfly, for instance, has red
spots and still is smooth ; but as it emits a strongly-
scented liquid when alarmed, it is probably dis-
tasteful to birds. I cannot recall any other case of
a British caterpillar which has conspicuous red
spots or lines, and yet is smooth.
9. Blue is, among caterpillars, even a rarer colour
than red. Indeed, among our larger larvae, the
only cases I can recall are the Lappets, which
have two conspicuous blue bands, the Death's-
head Moth, which has broad diagonal bands, and
two of the Hawk-moths, which have two bright
blue oval patches on the third segment. The
Lappets are protected by being hairy, but why they
have the blue bands I have no idea. It is inte-
resting, that both the other species frequent plants
which have blue flowers. The peculiar hues of
the Death's-head caterpillar, which feeds on the
potato, unite so beautifully the brown of the earth,
the yellow and green of the leaves, and the blue
90
The Colotirs of Animals.
of the flowers, that, in spite of its size, it can
scarcely be perceived unless the eye be focussed
exactly upon it.
10. The Oleander Hawk-moth is also an inter-
estmg case. Many of the Hawk-moth caterpillars
have eye-like spots, to which I shall have to allude
again presently. These are generally reddish or
yellowish, but in this species, which feeds on the
periwinkle, they are bright blue, and in form as
well as colour closely resemble the blue petals of
that flower. One other species, the Sharp-winged
Hawk-moth, also has two smaller blue spots, with
reference to which I can make no suggestion. It
is a very rare species, and I have never seen it.
Possibly, in this case, the blue spots may be an
inherited character, and have no reference to the
present habits. They are, at any rate, quite small.
11. No one who looks at any representations of
Hawk-moth caterpillars can fail to be struck by
the peculiar colouring of those belonging to the
Pine Moth, which differ in style of colouring from
all other sphinx larvae, having longitudinal bands
of brown and green. Why is this } Their habitat
is different. They feed on the leaves of the
pinaster, and their peculiar colouring offers a
general similarity to the brown twigs and narrow
green leaves of a conifer. There are not many
species of butterflies or moths which feed on the
pine, but there are a few : and most, if not all of
them, have a very analogous style of colouring
The Colours of Animals.
91
to that of the Pine Moth, while the latter has
also tufts of bluish-green hair which singularly
mimic the leaves of the pine. It is still more re-
markable that in a different order of insects we
again find species — ^for instance one of the saw-flies
— which live on the pine, and in which the same
style of colouring is repeated.
92
TJie Colours of Animals.
III.
1. Let us now take a single group, and see how
far we can explain its various colours and markings,
and what are the lessons which they teach us. For
this purpose, I think I cannot do better than select
the larvae of the hawk-moths, which have just been
the subject of a masterly work by Dr. Weissmann,
from which most of the following facts are taken.
The caterpillars of this group are very different
in colour — green, white, yellow, brown, sometimes
even gaudy, varied with spots, patches, streaks, and
lines. Now, are these differences merely casual
and accidental, or have they a meaning and a pur-
pose } In many, perhaps in most cases, the mark-
ings serve for the purpose of concealment. When,
indeed, we see caterpillars represented on a white
sheet of paper, or if we put them on a plain table,
and focus the eye on them, the colours and markings
would seem, if possible, to render them even more
conspicuous ; but amongst the intricate lines and
varied colours of foliage and flowers, and if the
insect be a little out of focus, the effect is very
different.
2. Let us begin with the Elephant Hawk-moth.
The caterpillars (fig. 13), as represented in most
entomological works, are of two varieties, most of
The Colours of A nimals.
93
them brown, but some green. Both have a whi e
Hne on the three first segments ; two remarkable
eye-like spots on the fourth and fifth, and a very
:-MOTH
;PHANT ;
n. Natl
r" w
fi o
■r! 3
o
U «
bj3
faint median line ; and are rather more than four
inches long. I will direct your attention specially,
for the moment, to three points : — What do the
94
The Colours of Animals.
eye-spots and the faint lateral line mean ? and why
are some green and some brown, offering thus such
a marked contrast to the leaves of the small epilobe
on which they feed ? Other questions will suggest
themselves later. I must now call your attention
to the fact that, when the caterpillars first quit the
egg, and come into the world (fig. 14), they are
Y
Tig. 14.— The Caterpillar of the Elephant Hawk-moth
{CheBrocampa elpenor). First Stage.
quite different in appearance, being, like so many
other small caterpillars, bright green, and almost
exactly the colour of the leaves on which they feed.
That this colour is not the necessary or direct con-
sequence of the food, we see from the case of
quadrupeds, which, as I need scarcely say, are never
green. It is, however, so obviously a protection to
small caterpillars, that this explanation of their
green colour suggests itself to every one.
3. After five or six days, and when they are about
a quarter of an inch in length, they go through their
first moult. In their second stage (fig. 15), they have
two white lines, stretching along the body from the
horn to the head; and after a few days (fig. 16),
but not at first, traces of the eye-spots appear on
the fourth and fifth segments, shown by a slight
The Colours of Animals.
95
Fig. 1 5. —The Caterpillar of the Elephant Hawk-moth
{Chcerocampa elpcnor). Second Stage.
I ^ — 1
Fig. 16.— The Caterpillar of the Elephant Hawk-moth
( Charocampa elpenor). Just before the second moult.
Fig. 17. — The Caterpillar of the Elephant Hawk-moth
{Chceroca?npa elfetior). Third Stage.
Fig. 18. — The Caterpillar of the Elephant FIawk-moth
{Charocampa elpenor). Fourth Stage.
96
The Colours of Animals.
wave in the upper line. After another five or six
days, and when about half an inch in length, our
caterpillars moult again. In their third stage (fig.
17), the commencement of the eye-spots is more
marked, while, on the contrary, the lower longitu-
dinal line has disappeared. After another moult
(fig. 18), the eye-spots are still more distinct, the
white gradually becomes surrounded by a black
line, while in the next stage (fig. 19) the centre
becomes somewhat violet. The white lines have
almost or entirely disappeared, and in some speci-
mens faint diagonal lines make their appearance.
Some few assume a brownish tint, but not many.
A fourth moult takes place in seven or eight days,
and when the caterpillars are about an inch and a
half in length. Now, the difference shows itself
still more between the two varieties, some remain-
ing green, while the majority become brown. The
eye-spots are more marked, and the pupil more
distinct, the diagonal lines plainer, while the white
line is only indicated on the first three, and on the
eleventh segment. The last stage (fig. 19) has been
already described.
4. Now, the principal points to which I wish to
draw attention are (i) the green colour, (2) the
longitudinal lines, (3) the diagonal lines, (4) the
brown colour, and (5) the eye-spots.
As regards the first three, however, I think I
need say no more. The value of the green colour
to the young larva is obvious ; nor is it much less
The Colours of Animals.
97
clear that when the insect is somewhat larger, the
longitudinal lines are a great advantage, while
subsequently diagonal ones become even more
important. «
5. The next point is the colour of the mature
caterpillars. We have seen that some are green, and
others brown. The green ones are obviously merely
those which have retained their original colour.
H
98
The Colours of Animals.
Now for the brown colour. This probably makes
the caterpillar even more conspicuous among the
green leaves than would otherwise be the case.
Let us see, then, whether the habits of the insect
will throw any light upon the riddle. What
would you do if you were a big caterpillar Why,
like most other defenceless creatures, you would
feed by night, and lie concealed by day. So do
these caterpillars. When the morning light comes,
they creep down the stem of the food plant, and
lie concealed among the thick herbage, and dry
sticks and leaves, near the ground ; and it is ob-
vious that under such circumstances the brown
colour really becomes a protection. It might in-
deed be argued that the caterpillars, having become
brown, concealed themselves on the ground ; and
that we were, in fact, reversing the state of things.
But this is not so ; because, while we may say, as
a general rule, that (with some exceptions due to
obvious causes) large caterpillars feed by night and
lie concealed by day, it is by no means always the
case that they are brown ; some of them still retain-
ing the green colour. We may then conclude that
the habit of concealing themselves by day came
first, and that the brown colour is a later adapta-
tion. It is, moreover, interesting to note that while
the caterpillars which live on low plants often go
down to the ground and turn brown, those which
feed on large trees or plants remain on the under
side of the leaves, and retain their green colour.
The Colours of Animals.
99
6. Thus, in the Eyed Hawk-moth, which feeds on
the willow and sallow ; the Poplar Hawk-moth
which feeds on the poplar ; and the Lime Hawk-
moth, which frequents the lime, the caterpillars all
remain green ; while in those which frequent low
plants, such as the Convolvulus Hawk-moth, which
frequents the convolvulus ; the Oleander Hawk-
moth, which feeds in this country on the periwinkle ;
and other species, most of the caterpillars turn
brown. There are, indeed, some caterpillars which
are brown, and still do not go down to the ground
— as, for instance, those of the Geomeiridce gene-
rally. These caterpillars, however, as already
mentioned, place themselves in peculiar attitudes,
which, combined with their brown colour, make
them look almost exactly like bits of stick or dead
twigs.
7. The last of the five points to which I called your
attention was the eye-spots. In some cases, spots
may serve for concealment, by resembling the
marks on dead leaves. In one species, which feeds
on the hippophae, or sea buckthorn, a grey-green
plant, the caterpillar also is a similar grey-green,
and has, when full grown, a single red spot on each
side — which, as Weissmann suggests, at first sight
much resembles in colour and size one of the berries
of the hippophae. This might, at first, be sup-
posed to constitute a danger, and therefore to be
a disadvantage; but the seeds, though present,
are not ripe, and consequently are not touched by
H 2
100
The Colours of Aniiiials.
birds. Again, in another caterpillar, there is an eye-
spot on each segment, which mimics the flower of
the plant on which it feeds. White spots, in some
cases, also resemble the spots of light which pene-
trate foliage. In other instances, however, and at
any rate in our Elephant Hawk-moth, the eye-spots
certainly render the insect more conspicuous.
8. Now in some cases, this is an advantage,
rather than a drawback. Suppose that from the
nature of its food, from its being covered with
hair, or from any other cause, a small green cater-
pillar were very bitter, or disagreeable or dan-
gerous as food, still, in the number of small gi-een
caterpillars which birds love, it would be continually
swallowed by mistake. If, on the other hand, it
had a conspicuous and peculiar colour, its evil taste
would serve to protect it, because the birds would
soon recognise and avoid it, as has been proved ex-
perimentally. I have already alluded to a case of
this among the Hawk-moths, in a species which,
feeding on euphorbia, with its bitter milky juice,
is very distasteful to birds, and is thus actually
protected by its bold and striking colours. The
spots on our Elephant Hawk-moth caterpillar do
not admit of this explanation, because the insect is
quite good to eat-— I mean, for birds. We must,
therefore, if possible, account for these spots in
some other way. There can, I think, be little
doubt that Weissmann is right when he suggests
that the eye-spots actually protect the caterpillar,
by frightening its foes.
The Colours of Animals.
lOl
9. Every one must have observed that these large
caterpillars — as, for instance, that of the small
Elephant Hawk-moth (fig. 20)— have a sort of
uncanny poisonous appearance ; that they suggest
a small thick snake or other evil beast, and the
so-called "eyes" do much to increase the deception.
Moreover, the segment on which they are placed is
102
The Colours of Animals.
swollen, and the insect, when in danger, has the
habit of retracting its head and front segments,
which gives it an additional resemblance to some
small reptile. That small birds are, as a matter of
fact, afraid of these caterpillars (which, however, I
need not say, are in reality altogether harmless),
Weissmann has proved by actual experiment. He
put one of these caterpillars in a tray, in which he
was accustomed to place seed for birds. Soon a
little flock of sparrows and other small birds assem-
bled to feed as usual. One of them lit on the edge
of this tray, and was just going to hop in, when
she spied the caterpillar. Immediately she began
bobbing her head up and down, but was afraid to
go nearer. Another joined her, and then another,
until at last there was a little company of lo or
12 birds, all looking on in astonishment, but
not one ventured into the tray ; while one bird,
which lit in it unsuspectingly, beat a hasty retreat
in evident alarm, as soon as she perceived the
caterpillar. After watching for some time, Weiss-
mann removed it, when the birds soon attacked
the seeds. Other caterpillars also are probably
protected by their curious resemblance to spotted
snakes.
10. Moreover, we may learn another very interest-
ing lesson from these caterpillars. They leave the
egg, as we have seen, a plain green, like so many other
caterpillars, and gradually acquire a succession of
markings, the utility of which I have just attempted
The Colours of Animals.
103
to explain. The young larva, in fact, represents
an old form, and the species, in the lapse of ages,
has gone through the stage which each individual
now passes through in a few weeks. Thus, the
caterpillar of Chcerocampa porcellus, a species very
nearly allied to the Elephant Hawk-moth, passes
through almost exactly the same stages as that spe-
cies. But it leaves the egg with a subdorsal line,
which the caterpillar of the Elephant Hawk-moth
does not acquire until after its first moult. No
one can doubt, however, that there was a time
when the new-born caterpillars of the small' Ele-
phant Hawk-moth were plain green, like those of
the large one. Again, if we compare the mature
caterpillars of this group of hawk-moths, we shall
find there are some forms which never develop eye-
spots, but which, even when full grown, correspond
to the second stage of the Elephant Hawk-moth.
Here, then, we seem to have species still in the
stage which the Elephant Hawk-moth must have
passed through long ago.
I04
The Colours of Animals.
IV.
I. The genus Deilephila, of which we have In Eng-
land three species — the Euphorbia Hawk-moth,
the Galium Hawk-moth, and the Rayed Hawk-
moth— is also very instructive. The caterpillar of
the Euphorbia Hawk-moth begins life of a clear
green colour, without a trace of the subsequent
markings. After the first moult, however, it has a
number of black patches, a white line, and a series of
white dots, and has, therefore, at one bound, acquired
characters which in the Elephant Hawk-moth, as
we have seen, were only very gradually assumed.
In the third stage, the line has disappeared, leaving
the white spots. In the fourth, the caterpillars have
become very variable, but are generally much darker
than before, and have a number of white dots under
the spots. In the fifth stage, there is a second row
of white spots under the first. The caterpillars
not being good to eat, there is, as has been already
pointed out, no need for, or attempt at, concealment.
Now if we compare the mature caterpillars of other
species of the genus, we shall find that they repre-
sent phases in the development of the Euphorbia
Hawk-moth. The Sea Buckthorn Hawk-moth,
for instance, even when full grown, is a plain green,
with only a trace of the line, and corresponds, there-
The Colours of Animals.
fore, with a very early stage of the Euphorbia Hawk-
moth ; there is another species found in South
Russia, which has the Hne, and represents the second
stage of the Euphorbia Hawk-moth ; another has
the Hne and the row of spots, and represents,
therefore, the third stage; lastly, there are some
which have progressed further, and lost the longi-
tudinal line, but they never acquire the second row
of spots which characterises the last stage of the
Euphorbia Hawk-moth.
2. Thus, then, the individual life of certain cater-
pillars gives us a clue to the history of the species
in past ages.
For such inquiries as this, the larvze of Lepidop-
tera are particularly suitable, because they live an
exposed life ; because the different species, even of
the same genus, often feed on different plants, and
are therefore exposed to different conditions ; and
last, not least, because we know more about the
larvae of the butterflies and moths than about those
of any other insects. The larvae of ants all live in the
dark ; they are fed by the perfect ants, and being
therefore all subject to very similar conditions, are
all very much alike. It would puzzle even a good
naturalist to determine the species of an ant larva,
while, as we all know, the caterpillars of butterflies
and moths are as easy to distinguish as the perfect
insects ; they differ from one another as much as,
sometimes more than, the butterflies and moths
themselves.
io6 The Colours of Animals.
3. There are five principal types of colouring
among caterpillars. Those which live inside wood,
or leaves, or underground, are generally of an uni-
form pale hue ; the small leaf-eating caterpillars
are green, like the leaves on which they feed. The
other three types may, to compare small things with
great, be likened to the three types of colouring
among cats. There are the ground cats, such as
the lion or puma, which are brownish or sand
colour, like the open places they frequent. So also
caterpillars which conceal themselves by day at the
roots of their food-plant, tend, as we have seen,
even if originally green, to assume the colour of
earth. Nor must I omit to mention the Geometridoe,
to which I have already referred, and which, from
their brown colour, their peculiar attitudes, and the
frequent presence of warts or protuberances, closely
mimic bits of dry stick. That the caterpillars of
these species were originally green, we may infer
from the fact that some of them at least are still of
that colour when first born.
4. Then there are the spotted or eyed cats, such
as the leopard, which live among trees; and their
peculiar colouring renders them less conspicuous
by simulating spots of light which penetrate through
foliage. So also many caterpillars are marked with
spots, eyes, or patches of colour. Lastly, there are
the jungle cats, of which the tiger is the typical
species, and which have stripes, rendering them
very difficult to see among the brown grass which
The Colours of Animals.
107
they frequent. It may, perhaps, be said that this
comparison fails, because the stripes of tigers are
perpendicular, while those of caterpillars are either
longitudinal or oblique. This, however, so far from
constituting a real difference, confirms the explana-
tion; because in each case the direction of the lines
follows that of the foliage. The tiger, walking
horizontally on the ground, has transverse bars ;
the caterpillar, clinging to the grass in a vertical
position, has longitudinal lines; while those which
live on large-veined leaves have oblique lines, like
the oblique ribs of the leaves.
5. It might, however, be suggested that the cases
given above are exceptional. I have, therefore, in
another work, tabulated all our larger British cater-
pillars, and the result is very interesting. As regards
butterflies, we have 66 species, out of which 1 8 are
spiny, and two may fairly be called hairy. I do
not speak of mere pubescence, but of true hairs and
spines. Now, out of these 20, 10 are black, two
greyish, six brown or brownish, one greyish-green,
and only one green. Thus, while green is so pre-
ponderating a colour among smooth-skinned or
ordinarily pubescent* caterpillars (37 out of the
66 species of butterflies being of this colour), only
a single spiny species is thus coloured.
6. Now let us look at these numbers under a
different aspect. Out of 66 species 10 are black;
and, as we have already seen, all these are spiny or
* " Pubescent" means covered with very short fine hairs.
io8
Tlie Colours of Animals.
hairy. The caterpillar of the Crimson-ringed But-
terfly—a species reputed to have been taken in this
country— is stated to be black, and is not hairy or
spiny ; but, as it has red spots and blue tubercles,
and the neck is furnished with a yellow forked
appendage, it is probably sufficiently protected.
The larva of the Swallow-tail Butterfly is also
marked with black, and provided with strongly-
scented tentacles, which probably serve as a pro-
tection.
Again, there are i6 brown species, and of these
seven are hairy or spiny.
7. Red and blue are rare colours among cater-
pillars. Omitting minute dots, we have six species
more or less marked with red or orange.* Of these,
two are spiny, two hairy, and one protected by scent-
emitting tentacles. The orange medio-dorsal line
of the Bedford Butterfly! is not very conspicuous,
and has been omitted in some descriptions. Blue
is even rarer than red ; in fact, none of our butter-
fly larvae can be said to exhibit this colour.
8. Now let us turn to the moths. I have taken all
the larger species, amounting to rather more than
\20;% out of which 68 are hairy or downy; and
* These are A. aglaia, V. antiopa, N. lucina, C. alstts, P. cratagi,
and P. machaon.
t Cupido alsus.
% The Hepialida:, Zeuzeridce, and Sesidce have been omitted,
because these larva are all internal or subterranean feeders, and are
devoid of any striking colour.
The Colours of Animals.
109
of these 48 arc marked with black or grey, 15
brown or brownish, two yellowish-green, one bluish-
grey, one striped with yellow and black, and one
reddish-grey. There are two yellowish-green hairy
species, which might be regarded as exceptions :
one, that of the Five-spotted Burnet-moth, is
marked with black and yellow, and the other*
is variable in colour, some specimens of this cater-
pillar being orange. This last species is also marked
with black, so that neither of these species can be
considered of the green colour which serves as a
protection. Thus, among the larger caterpillars,
there is not a single hairy species of the usual
green colour. On the other hand, there are 50
species with black or blackish caterpillars, and of
these 48 are hairy or downy.
9. In 10 of our larger moths the caterpillars are
more or less marked with red. Of these, three are
hairy, one is an internal feeder, four have reddish
lines, which probably serve for protection by simu-
lating lines of shadow, and one, the Euphorbia
Hawk-moth, is inedible. The last, the striped
Hawk-moth, is rare, and I have never seen the
caterpillar ; but to judge from figures, the reddish
line and spots would render it, not more, but less
conspicuous amongst the low herbage which it
frequents.
10. Seven species only of our larger moths have
any blue ; of these, four are hairy, the other three are
* Nola albtilalis.
I lO
The Colours of Animals.
hawk-moths. In one, the Death's Head, the violet
colour of the side stripes certainly renders the insect
less conspicuous among the flowers of the potato,
on which it feeds. In the Oleander Hawk-moth
there are two blue patches, which, both in colour
and form, curiously resemble the petals of the
periwinkle, on which it feeds. In the third species,
the small Elephant Hawk-moth, the bluish spots
form the centres of the above-mentioned eye-like
spots.
II. In one family,* as already mentioned, the
caterpillars are very often brown, and closely re-
semble bits of stick, the similarity being much in-
creased by the peculiar attitudes they assume. On
the other hand, the large brown caterpillars of certain
Hawk-moths are night feeders, concealing them-
selves on the ground by day ; and it is remarkable
that while those species, such as the Convolvulus
Hawk-moth, which feed on low plants, turn brown
as they increase in age and size, others, which
frequent trees, and cannot therefore descend to
the ground for concealment, remain green through-
out life. Omitting these, there are among the
larger species, 17 which are brown, of which 12
are hairy, and two have extensile caudalt filaments.
The others closely resemble bits of stick, and place
themselves in peculiar and stiff attitudes.
* The Geometridx.
t .£'x/^M«V^= capable of being extended; CVi«(fa/= belonging to
the tail.
The Colours of A ninials.
12. And thus, summing up the caterpillars, both
of butterflies and moths, out of 88 spiny and
hairy species, only one is green,* and even this
may not be protectively coloured, since it has
conspicuous yellow warts. On the other hand, a
very great majority of the black and brown cater-
pillars, as well as those more or less marked with
blue and red, are either hairy or spiny, or have
some special protection.
13. Here, then, I think we see reasons, for many
at any rate, of the variations of colour and markings
in caterpillars, which at first sight seem so fan-
tastic and inexplicable. I should, however, produce
an impression very different from that which I wish
to convey, were I to lead you to suppose that all
these varieties have been explained, or are under-
stood. Far from it ; they still offer a large fiield
for study ; nevertheless, I venture to think the
evidence now brought forward, however imper-
fectly, is at least sufficient to justify the conclusion
that there is not a hair or a line, not a spot or
a colour, for which there is not a reason — which
has not a purpose or a meaning in the economy of
nature.
* Z. syiilla.
Fij-, 21.— White Deadnettle {Lamium alburn).
SECTION IV.— ON FLOWERS AND
INSECTS.
I.
1. The flower of the common White Deadnettle
(fig. 22) consists of a narrow tube, somewhat ex-
panded at the upper end (fig. 23), where the lower
lobe of the corolla forms a platform, on each side of
which is a small projecting tooth (fig. 23, ni). The
upper portion of the corolla is an arched hood
(fig. 23, co), under which lie four anthers {a a), in
pairs, while between them, and projecting some-
what downwards, is the pointed pistil {st). At the
On Fhnucrs and Insects. 1 1 3
lower part, the tube contains honey, and above the
honey is a row of hairs almost closing the tube.
Now, why has the flower this peculiar form ? What
regulates the length of the tube ? What is the use
of this arch ? What lessons do these teeth teach
Fig. 22. — Flower of White Deadnettle {Lammtn album).
Fig. 23. — Section of the Flower of the White Deadnettle
{Lammm album).
US What advantage is the honey to the flower
Of what use is the fringe of hairs } Why does the
stigma project beyond the anthers } Why is the
corolla white, while the rest of the plant is green
2. Similar questions may of course be asked with
I
114
On Flowers and Insects.
reference to other flowers. Let us see whether we
can throw any light upon them.
Before, however, proceeding further, let me briefly
mention the terms used in describing the different
parts of a flower.
If we examine a common flower we shall find that
Fig. 24. — Meadow Geranium {Geranium pratense).
it consists, firstly, of an outer envelope or calyx,
sometimes tubular, sometimes consisting of separate
leaves called sepals ; secondly, an inner envelope or
corolla, which is generally more or less coloured,
and which, like the calyx, is sometimes tubular,
sometimes composed of separate leaves called
I
On Flowers and Insects.
petals ; thirdly, of one or more stamens, consisting
of a stalk or filament, and a head or anther, in
which the pollen is produced ; and fourthly, ^. pistil,
which is situated in the centre of the flower, and
consists generally of three principal parts : one or
more compartments at the base, each containing one
or more seeds ; the stalk or style ; and the stigma,
which in many familiar instances forms a small
head at the top of the style or ovary, and to which
the pollen must find its way in order to fertilise
the flower.
3. At the close of the last century, Conrad
Sprengel, a German schoolmaster, published a valu-
able work on flowers, in which he pointed out that
the forms and colours, the scent, honey, and general
structure of flowers, have reference to the visits of
insects, which are of importance in transferring the
pollen from the stamens to the pistil. This admir-
able work, however, did not attract the attention it
deserved, and remained almost unknown until
Mr. Darwin devoted himself to the subject. Our
illustrious countryman was the first clearly to per-
ceive that the essential service which insects perform
to flowers, consists not only in transferring the
pollen from the stamens to the pistil, but in trans-
ferring it from the stamens of one flower to the
pistil of another. Sprengel had indeed observed
in more than one instance that this was the case,
but he did not altogether appreciate the importance
of the fact.
I 2
ii6
On Floivers and Insects.
4, Mr. Darwin, however, has not only made it
clear from theoretical considerations, but has also
proved it, in a variety of cases, by actual experiment.
More recently Fritz Miiller has even shown that in
some cases pollen, if placed on the stigma of the
same flower, has no more effect than so much in-
organic dust.
In by far the majority of cases, the relation
between flowers and insects is one of mutual ad-
vantage. In some plants, however — as, for instance,
in our Common Sundew — we find a very different
state of things, and the plant catches and devours
the insects. The first observation on insect-eating
flowers was made about the year 1768 by our
countryman Ellis. He observed that in a certain
North American plant the leaves have a joint in
the middle, and thus close over, kill, and actually
digest any insect which may alight on them.
5. In our common Sundew (fig. 25) the rounded
leaves are covered with hairs, which are swollen
and glutinous at the tip. Of these hairs there
are on an average about 200 on a full-sized leaf
The tips of the hairs are each surrounded by a
drop of an exceedingly viscid solution, which,
glittering in the sun, has given rise to the name of
the plant. If any object be placed on the leaf,
these glandular hairs slowly fold over it, and en-
close it. If, for instance, any small insect alights
on the leaf it becomes entangled in the glutinous
secretion, the glands close over it, their secretion if^
On Floivers and Insects.
117
increased, and they literally digest their prey. It
has been recently shown that plants supplied with
insects grow more vigorously than those not so
fed. If, on the other hand, a small stone, or any
other substance which contains no nourishment,
be placed on the leaf, though the hairs at first
close over it, they soon open again. It is very
Fig. 25. — Common Sundew {Drosera rotundifolid).
curious that while the glands are so sensitive that
an object weighing only rsTToth of a grain placed
on them is sufficient to cause motion, yet they are
"insensible to the weight and repeated blows of
drops" of even heavy rain.
6. The Sundew, however, is not our only English
insectivorous plant. In the Butterwort, which fre-
ii8
On Flotvers and hisects.
quents moist places, generally on mountains, the
leaves are concave with incurved margins, and the
upper surfaces are covered with two sets of glan-
dular hairs. In this case the naturally incurved
edges curve over still more if a fly or other insect
be placed on the leaf.
7. Another case is that of the Bladderwort
Fig. 26. — Common Bladderwort {Uirictilaria vulgaris).
(fig. 26), an aquatic species, which bears a number
of little bags which have been supposed to act as
floats. Branches, however, which bear nobladderfloat
just as well as the others, and there seems no doubt
that the real use of these little bags is to capture
small aquatic animals, which they do in considerable
numbers. The bladders, in fact, are on the prin-
On Floivers and Insects.
119
ciple of an eel-trap, having an entrance closed with
a flap which permits an easy entrance, but effec-
tually prevents the unfortunate victim from getting
out again.
8. I will only allude to one foreign case, that of
the Sarracenia. In this genus some of the leaves
are in the form of a pitcher. They secrete a fluid,
and are lined internally with hairs pointing down-
wards. Up the outside of the pitcher there is a line
of honey glands, which lure the insects to their des-
truction. Flies and other insects which fall into
this pitcher cannot get out again, and are actually
digested by the plant. Bees, however, are said to
be scarcely ever caught.
120
On Floivers and Insects.
II.
1. Every one knows how important flowers are to
insects ; every one knows that bees, butterflies, &c.,
derive the main part of their nourishment from the
honey or pollen of flowers, bnt comparatively few
are aware, on the other hand, how much the flowers
themselves are dependent on insects. Yet it has,
I think, been clearly shown that if insects have
been in some respects modified and adapted with a
view to the acquirement of honey and pollen,
flowers, on the other hand, owe their scent and
honey, their form and colour, to the agency of
insects. Thus the lines and bands by which so
many flowers are ornamented have reference to the
position of the honey ; and it may be observed that
these honey-guides are absent in flowers which open
at night, where they of course would not show,
and would therefore be useless. Flowers, more-
over, which are generally pale — for instance, the
White Lychnis — open in the evening ; while those
of a deeper hue, such as the Red Lychnis, flower
by day.
2. Indeed, it may be laid down as a general rule,
that those flowers which are not fertilised by honey-
seeking insects — as, for instance, those of the Dock
(fig. 27), the Beech, and most other forest trees—
On Floivers and Insects.
121
are small in size, and do not possess either colour,
scent, or honey.
Though the pistil is generally surrounded by a
row of stamens, there are comparatively few cases
in which the pollen of the latter falls directly
on the former. On the contrary, this transference
is in most cases effected in other ways, generally
Fig. 27. — Broad Dock {Rumex obtusifolius).
by means of the wind, of insects, or, in some cases,
of birds. In the former case, however, by far the
greater part of the pollen is wasted ; and much more
must therefore be produced than in those cases
where it is carried by insects.
3. One advantage, of course, is the great economy
of pollen. We have not much information on the
122
Oji Flowers and Insects.
subject, but it would seem, from the few observa-
tions that have been made, that half a dozen pollen
grains are sufficient to fertilise a seed. But in
plants in which the pollen is carried by the wind,
the chances against any given grain reaching the
pistil of another flower are immense. Consequently
by far the greater part of the pollen is lost. Every
one, for instance, must have observed the clouds of
pollen produced by the Scotch Fir. In such flowers
as the Pceony the pollen is ca.rried by insects, and
far less therefore is required ; yet even here the
quantity produced is still large ; it has been esti-
mated that each flower produces between 3,000,000
and 4,000,000 grains. The Dandelion is more spe-
cialised in this respect, and produces far less pollen,
about 240,000 grains to each flower ; while in the
common Avens only ten times more pollen is pro-
duced than is actually used in fertilisation.
4. It might, however, be at first supposed that
where stamens and pistil co-exist in the same flower,
the pollen from the one could easily fall on and
fertilise the other. And in fact this does occur in
some species ; but, as we have seen, it is a great
advantage to a species that the flower should be
fertihsed by pollen from a different stock. How
then is self-fertilisation prevented
There are three principal modes.
Firstly, in many plants the stamens and pistil are
in separate flowers, sometimes situated on different
plants.
On Flowers and Insects.
123
Secondly, even when the stamens and pistil are
in the same flower, they are in many species not
mature at the same time; this was first observed
by Sprengel as long ago as 1790; in some cases
the stigma has matured before the anthers are ripe,
while in other and more numerous cases the anthers
have ripened and shed all their pollen before the
stigma has come to maturity.
Thirdly, there are many species in which, though
the anthers and stigma are contained in the same
flower and are mature at the same time, they are
so situated that the pollen can hardly reach the
stigma of the same flower.
5. The transference of the pollen from one flower
to another is, as already mentioned, effected princi-
pally either by the wind or by insects.
Wind-fertilised flowers, as a rule, have no colour,
emit no scent, produce no honey, and are regular
in form. Colour, scent, and honey are the three
characteristics by which insects are attracted to
flowers.
As a rule, wind-fertilised flowers produce much
more pollen than those which are fertilised by
insects. This is necessary, because it is obvious
that the chances against any given pollen grain
reaching the stigma are much greater in the one
case than in the other. Every one, as already
mentioned, has observed the showers of yellow
pollen produced by the Scotch Fir.
6. Again, it is an advantage to wind-fertilised
1 24 On Flozvers and Insects.
plants to flower early in the spring before the leaves
are out, because the latter would catch much of the
pollen, and thus interfere with its access to the
stigma. Again, in these plants the pollen is less
adherent, so that it can easily be blown away by
the wind, which would be a disadvantage in most
plants which are fertilised by insects.
Such flowers generally have the stigma more or
less branched or hairy, which evidently must tend
to increase their chances of catching the pollen.
7. The evidence derivable from the relations of
bees and flowers is probably sufficient to satisfy-
most minds that bees are capable of distinguishing
colours, but the fact had not been proved by any
conclusive experiments. I therefore tried the fol-
lowing. If you bring a bee to some honey, she
feeds quietly, goes back to the hive, stores away
her honey, and returns with or without companions
for another supply. Each visit occupies about six
minutes, so that there are about 10 in an hour,
and about 100 in a day. I may add that in this
respect the habits of wasps are very similar, and
that they appear to be quite as industrious as bees.
Perhaps I may give the record of a morning's work
of one of my wasps.* She came to the honey at a
few minutes after 4 in the morning, and to show
how regularly she worked I may give the following
extract from my note-book, recording her visits
from 6.30 till 12. Thus she—
* In her case the intervals were rather longer than usual
On Flowers and Insects. I2S
Came again at 6.29,
and returned at 6.32
6.41
6.44
J )
6.55
>»
7
) >
7.11
) »
7-15
) )
7-23
7. 20
) )
7-37
! J
7.42
»»
7.56
> )
8-3
) »
8.11
J J
0.14
J »
8.20
J>
0.24
I )
8.31
) )
8.34
) »
8.40
) >
0.42
)>
8.50
J J
8.52
)r
8.58
) »
9
) »
9.8
» )
9.11
J J
9.18
) )
9.22
))
9-30
))
9-32
) )
9-39
) »
9.40
j»
9- SO
) >
9- 54
) )
10. 1
) J
10. 5
5»
10.14
) J
io'i7
))
10.25
7>
10.28
) J
10.37
) »
10.40
) )
10.47
) »
10.51
» J
II
>»
II. 6
) )
II. 17
I >
11.20
» »
11-34
) J
11-37
11.50
» 1
"•53
12.5
> J
12.8
and so on till half-past 7 in the evening. Thus
she worked twelve hours like a man, and performed
more than 100 journeys to and fro.* This, how-
* Mr. Darwin, in his last work, brought forward .some striking
evidence how rapidly bees work. They visit, it appears, 20 flowers
in a minute, and so carefully do they economise the sunny hours,
that in flowers with several nectaries if they find one dry, they do
126
On Flowers and Insects.
ever, was in autumn ; in summer they make over-
time, and work on till late in the evening.
8. I have already mentioned some experiments
which show clearly that bees can distinguish colours.
They appear fortunately to prefer the same colours
as we do. On the contrary, flowers of a livid,
yellow, or fleshy colour are most attractive to flies ;
and moreover, while bees are attracted by odours
which are also agreeable to us, flies, as might
naturally be expected from the habits of their
larvae, prefer some which to us seem anything but
pleasant.
not waste time by examining the others on the same plant. Mr.
Darwin watched carefully certain flowers, and satisfied himself that
each one was visited by bees at least thirty times in a day. The
result is, that even where flowers are very numerous— as, for in-
stance, on heathy plains and in clover fields— every one is visited
during the day. Mr. Darwin carefully examined a large number
of flowers in such cases, and found that every single one had been
visited by bees.
On Flowers and Insects.
127
Fig. 28. — Common Willow Herb {Epilobium angustifolium).
III.
I . Among other obvious evidences that the beauty
of flowers is useful in consequence of its attracting
insects, we may adduce those cases in which the
transference of the pollen is effected in different
manners in nearly allied plants, sometimes even in
the same genus.
Thus, the Common Mallow (fig. 29) and Dwarf
Mallow (fig. 30), which grow in the same localities,
and therefore must come into competition, are
nevertheless nearly equally common.
In the Common Mallow, however, where the
128 On Flowers and Insects.
branches of the stigma are so arranged (fig.
that the plant cannot fertihse itself, the petals are
large and conspicuous, so that the plant is visited
Fig. 30. — Dwarf Mallow [Malva rotundifolia).
by numerous insects; while in the Dwarf Mallow
(fig. 32), the flowers of which are comparatively
small and rarely visited by insects, the branches of
the stigma are elongated, and twine themselves
On Floiuers and Insects.
129
among the stamens, so that the flower readily
fertilises itself.
2. Another interesting case is afforded by the
Fig. 31- Fig. 32.
Stamen-, and Stigmas of the Common Mallow {Malva sylvestris)
and the Dwarf Mallow [Malva rotundifolia).
Fig. 33. —Common Willow Herb {Epilob'mm angusiifolium).
Willow Herbs. The Common Willow Herb (fig.
33) has large purplish flowers in conspicuous heads,
and is much frequented by insects ; while the
K
^ On Flozvers and Insects.
Hoary Willow Herb (fig. 34) has small solitary
flowers, and is seldom visited by insects. Now in
the former species their visits are necessary, because
the stamens ripen and shed their pollen before the
pistil, so that the flower is consequently incapable
of fertilising itself. In the latter species, on the
contrary, the stamens and pistil Come to maturity at
the same time.
3. Let us take another case, that of certain Gera-
■P"'g- 34-— Hoary Willow Herb {Epilobium parvifwriun).
niums. In the Meadow Geranium (fig. 35), which
has a very large flower, all the stamens open, shed
their pollen, and wither away, before the pistil comes
to maturity. The flower cannot, therefore, fertilise
itself, and depends entirely on the visits of insects
for the transference of the pollen. In the Moun-
tain Geranium, where the flower is not quite so
large, all the stamens ripen before the stigma, but
the interval is shorter, and the stigma is mature
before all the anthers have shed their pollen. It is,
On Flozvers and Insects.
therefore, not absolutely dependent on insects. In
the Dove's-foot Geranium, which has a still smaller
flower, five of the stamens come to maturity before
the stigma, but the last five ripen simultaneously
K 2
132
Oil Flowers and Insects.
with it. Lastly, in the Small-flowered Geranium,
which is least of all, the stigma ripens even before
the stamens. Thus, then, we have a series more or
less dependent on insects, from the Meadow Gera-
nium to which they are necessary, to the Small-
flowered Geranium which is quite independent of
them ; whilst the size of the corolla increases with
the dependence on insects.
In those species in which self-fertilisation is pre-
vented by the circumstance that the stamens and
pistil do not come to maturity at the same time,
the stamens generally ripen first.
4. The advantage of this is probably connected
with the visits of bees. In those flowers which
grow in bunches the lower ones generally open
first. Consequently in any given spike the flowers
are at first all staminate ; subsequently the lower
ones, being the older, have arrived at the pistillate
stage, while the upper ones are still staminate.
Now it is the habit of bees to begin with the lower
flowers of a spike and work upwards. A bee, there-
fore, which has already dusted herself with pollen
from another flower, first comes in contact with
the pistillate flowers, and dusts them with pollen,
after which she receives a fresh supply from the
upper staminate flowers, with which she flies to
another plant.
5. There are, however, some few species in
which the pistil ripens before the stamens. One
is our common Figwort. Now, why is this.?.
On Floivers and Insects,
133
Probably because the Figwort is one of our few
flowers specially visited by wasps, the honey being
not pleasing to bees. Wasps, however, unlike
bees, generally begin with the upper flowers and
pass downwards, and consequently in wasp flowers
it is an advantage that the pistil should ripen
before the stamens. But though the stamens
generally ripen before the pistil, the reverse some-
times occurs. Of this a very interesting case is
that of the genus Aristolochia. The flower is a
long tube, with a narrow opening closed by stiff
hairs which point backwards, so that it much re-
sembles an ordinary eel-trap. Small flies enter the
tube in search of honey, but from the direction of
the hairs it is impossible for them to return. Thus
they are imprisoned in the flower, until the stamens
have ripened and shed their pollen, by which the
flies get thoroughly dusted. Then the hairs of
the tube shrivel up, thus releasing the prisoners,
who carry the pollen to another flower.
6. Again, in our common Arums, the lords-and-
ladies of village lanes, the well-known green leaf
incloses a central pillar (fig. 36) ; near the base of
which are arranged a number of stigmas {st in the
accompanying figure), and above them several rows
of anthers {a). It might be supposed, therefore,
that the pollen from the anthers would fall on and
fertilise the stigmas. This, however, is not what
occurs. In fact the stigmas come to maturity first,
and have lost the possibihty of fertilisation before
134
Oft Flowers and Insects.
the pollen is ripe. The pollen must therefore be
brought by insects, and this is effected by small
flies, which enter the leaf, either for the sake of
honey or of shelter, and which, moreover, when
they have once entered the tube, are imprisoned
by the fringe of hairs {h). When the anthers
Fig. 36.— Common Arum. Diagrammatic Section.
h, hairs ; a, anthers ; st, stigmas.
ripen, the pollen falls on to the flies, which in their
efforts to escape get thoroughly dusted with it.
Then the fringe of hairs withers, and the flies, thus
set free, soon come out, and ere long carry the
pollen to another plant.
7. Now let us return to our White Deadnettle,
On Flowers and Insects.
J35
and see how far we can answer the questions which
I began by asking.
8, In the first place, the honey attracts insects.
If there were no honey, they would have no object
in visiting the flower. The bright colour is useful
in rendering the flower conspicuous. The platform
serves as an alighting stage for bees. The length
of the tube has reference to that of their proboscis,
and prevents the smaller species from obtaining
access to the honey, which would be injurious to
the flower, as it would remove the source of
attraction for the bees, without effecting the object
in view. The upper arch of the flower protects the
stamens and pistil, and also presses them firmly
against the back of the bee ; so that, when the bee
alights on the stage and pushes its proboscis down
to the honey, its back comes into contact with
them. The row of small hairs at the bottom of
the tube prevents small insects from creeping down
the tube and stealing the honey. Lastly, the small
processes on each side of the lower lip are the
rudimentary representatives of parts formerly more
largely developed, but which, having become use-
less, have almost disappeared.
9. In the Deadnettle it would appear that the
pistil matures as early as the stamens, and that cross-
fertilisation is attained by the relative position of
the stigma, which, as will be seen in the figure,
hangs down below the stamens ; so that a bee,
bearing pollen on its back from a previous visit to
13^ On Flowers and Insects.
another flower, would touch the pistil and transfer
to it some of the pollen, before coming in contact
with the stamens. In other species belonging to
the same great group or family of plants, the same
object is secured by the fact that the stamens come
to maturity before the pistil; they shed their
pollen, and shrivel up before the stigma is mature.
On Floivcrs and Insects.
137
IV.
I. Fig. 37 represents a young flower of Sage, in
which the stamens {ad) are mature, but not the
pistil (/), which moreover, from its position, is un-
touched by bees visiting the flower, as shown in
Fig. 37.— Sage (Salvia officinalis). Section of a young flower.
fig. 38. The anthers, as they shed their pollen,
gradually shrivel up ; while, on the other hand, the
pistil increases in length and curves downwards,
until it assumes the position shown in fig. 39, st,
where, as is evident, it must come in contact with
any bee visiting the flower, and would touch just
that part of the back on which pollen would be
deposited by a younger flower. In this manner
cross-fertilisation is effectually secured.
2. There are, however, several other curious points
138
On Floivcrs and Insects.
in which the Sage differs greatly from the species
last described.
The general form of the flower, indeed, is very
Fig. 38. — Sage [Salvia officinalis) visited by a bee.
Fig. 39.— Sage {Salvia officinalis). An older flower.
similar. We find again that, as generally in the
Labiates, the corolla has the lower lip adapted as
an alighting board for insects, while the arched
On Flozvers and Insects.
139
upper lip covers and protects the stamens and
pistils.
The arrangement and structure of the stamens
is, however, very peculiar and interesting. As in
the Deadnettle, they are four in number, but one
Fig. 41. — Stamens when moved by a bee.
pair is quite rudimentary (fig. 37, b). In the other
{an) the two anthers, instead of being attached
close together at the summit of the filament, are
separated by a long movable rod, called a con-
nective (figs. 40, 41, m), so that they can play freely
on the stalk of the stamen. In a natural position,
140 On Flozvers and Insects.
this connective is upright, so that the one anther is
situated (fig. 37) in the neck of the tube, the other
under the arched hood. The lower anther, more-
over, is more or less rudimentary. Now, when a
bee comes to suck the honey, it pushes the lower
anther out of the way with its head ; the result of
which is that the connective swings round, and the
upper fertile anther comes down on to the back of
the bee (figs. 38 and 41), and dusts it with honey,
just at the place where, in an older flower (fig. 39),
it would be touched by the stigma, st.
3. At first sight it may seem an objection to this
view that some species — as, for instance, the
common Snapdragon — the flower of which, accord-
ing to the above given tests, ought to be fertilised
by insects, is entirely closed, A little consideration,
however, will suggest the reply. The Snapdragon
is especially adapted for fertilisation by humble
bees. The stamens and pistil are so arranged that
smaller species would not effect the object. It is
therefore an advantage that they should be ex-
cluded, and in fact they are not strong enough to
move the spring. The Snapdragon is, so to say,
a closed box, of which the humble bees alone
possess the key.
4. The common Heath offers us a very ingenious
arrangement. The flower is in the form of an
inverted bell. The pistil represents the clapper,
and projects a little beyond the mouth of the bell.
The stamens are eight in number, and form a circle
On Fhivers and Insects.
round it, the anthers being united by their sides
into a continuous ring. Each anther has a lateral
hole, but as long as they touch one another, the
pollen cannot drop out. Each also sends out a
long process, so that the ring of anthers is sur-
rounded by a row of spokes. Now when a bee
comes to suck the honey, it first touches the end of
the pistil, on which it could hardly fail to deposit
some pollen, had it previously visited another plant.
It would then press its proboscis up the bell, in
doing which it would pass between two of the
spokes, and pressing them apart, would dislocate
the ring of anthers ; a shower of pollen would thus
fall from the open cells on to the head of the bee.
5. In many cases the effect of the colouring and
scent is greatly enhanced by the association of
several flowers in one bunch, or raceme ; as, for
instance, in the Wild Hyacinth, the Lilac, and other
familiar species. In the great family of Umbelli-
fera, this arrangement is still further taken advan-
tage of, as in the common Wild Chervil (fig. 42).
In this group the honey is not, as in the flowers
just described, situated at the bottom of a tube, but
lies exposed, and is therefore accessible to a great
variety of small insects. The union of the florets
into a head, moreover, not only renders them more
conspicuous, but also enables the insects to visit
a greater number of flowers in a given time.
6. It might at first be supposed that in such small
flowers as these self-fertilisation would be almost
142
On Flowers and Insects.
unavoidable. In most cases, however, the stamens
ripen before the stigmas.
The position of the honey on the surface of a
more or less flat disk renders it much more acces-
sible than in those cases in which it is situated at
the end of a more or less long tube. That of the
Fig. 42. — Wild Chervil {Chcei-ophyllum sylvestris).
Deadnettle, for instance, is only accessible to certain
humble bees ; while H. Miiller has recorded no less
than 73 species of insects as visiting the common
Chervil, and some plants are frequented by even a
larger number.
7. In the Composites, to which the common Daisy
and the Dandelion belong, the association of flowers
On Flozvcrs and Insects.
143
is carried so far, that a whole group of iiorets is
ordinarily spoken of as one flower. The Daisy, for
instance, is not really a flower, but a group of little
flowers on a single stalk. Let us take, for instance,
the common Feverfew, or large White Daisy (figs.
43, 44, 45). Each head consists of an outer row of
F'g- 43-— Floret of P'everfew [Chrysanthemum parthenium).
pistillate florets or little flowers, in which the tubular
corolla terminates on its outer side in a white leaf
or ray, which serves to make the flower more con-
spicuous, and thus to attract insects. The central
florets are tubular, and make up the central yellow
part of the flower-head. Each of these florets con-
tarns a circle of stamens, the upper portions of
just opened.
144 071 Flozuers a?id Insects.
which are united at their edges and at the top (fig.
43), so as to form a tube, within which is the
pistil. The anthers open inwards, so as to shed the
pollen into this box, the lower part of which is
Fig. 44. Fig. 45.
yig. 44. —Floret of Feverfew {Chrysanthemum partheniuvi),
somewhat more advanced,
fig. 45.— Floret of Feverfew [Chrysanthetnum parihenium),
with the stigmas expanded.
formed by the stigma, or upper part of the pistil.
As the latter elongates, it presses the pollen against
the upper part of the box, which at length is forced
open, and the pollen is pushed out (fig. 44)- Any
insect then alighting on the flower would carry off
On Flowers and hisecis.
H5
some of the pollen adhering to the under side of its
body. The upper part of the pistil terminates in
two branches (fig. 45, st), each of which bears a little
brush of hairs. These hairs serve to brush the pollen
out of the tube; while in the tube the two branches
are pressed close together, but at a later stage they
separate, and thus expose the stigmatic surfaces (fig.
45, st), on which an insect, coming from a younger
flower, could hardly fail to deposit some pollen.
The two stigmas in the ray florets of this White
Daisy have no brush of hairs ; and they would be
of no use, as these flowers have no stamens.
146 On Flowers and Insects.
Fig. 46. — Bird's-foot Trefoil {Lotus cernicuieUus),
V.
I. The Leguminosse, or Pea-tribe, present a num-
ber of beautiful contrivances. Let us take a com-
mon little Bird's-foot Trefoil (fig. 46). The petals
are five in number ; the upper one stands upright,
and is known as the standard (fig. 47, std) ; the two
lateral ones present a slight resemblance to wings
(fig. 47, w), while the two lower ones are united
along their edges, so as to form a sort of boat,
whence they are known as the "keel" (figs. 48,
49, k). The stamens, with one exception, are united
at their bases, thus forming a tube (figs. 50, 51, t),
surrounding the pistil, which projects beyond them
Oil Flowers and Insects.
147
Fig. 47- F'g- 48-
V
F'g- 47- — Flower ot Bird's-foot Trefoil (^Lotus corniculatus),
seen from the side and in front.
,, 48. — Ditto, after removal of the standard.
,, 49. — Ditto, after removal of the standard and wings.
,, 50. — Ditto, after removal of one side of the keel.
,, 51. — Terminal portion of fig. 50, more magnified.
c, entrance to the honey ; a, the free stamen; c, the place where
the wings lock with the keel; f, expanded ends of stamen i ;
X, filaments of sla.m£ns ; g,. tip of keel ; po, pollen ; st, stigma, •
L 2
148 On Flowers and Insects.
into a triangular space at the end of the keel. Into
this space the pollen is shed (fig. ^\,pd). It must
also be observed that each of the wings has a pro-
jection {c) which locks into a corresponding depres-
sion of the keel, so that if the wings are depressed
they carry the keel with them. Now when an
insect alights on the flower, its weight depresses
the wings, and as they again carry with them the
keel, the latter slips over the column of stamens,
thus forcing some of the pollen out at the end of
the keel and against the breast of the insect. As
soon as the insect leaves the flower, this resumes its
natural position, and the pollen is again snugly
protected. The arrangement in the Sweet Pea is
very similar, and if the wings are seized by the
fingers, and pressed down, this outpumping of the
pollen may be easily effected, and the mechanism
will then be more clearly understood.
2. It will be observed (fig. 50) that one stamen is
separated from the rest. The advantage of this, is
that it leaves a space through which the proboscis
of the bee can reach the honey, which is situated
inside the tube formed by the united stamens. In
those Leguminosae which have no honey, the sta-
mens are all united together. Such flowers are,
nevertheless, in spite of the absence of honey, visited
by insects for the sake of the pollen alone.
In other Leguminosae — as, for instance, in the
Furze and the Broom — the flower is in a state of
tension, but the different parts are., as it were,
On Flozvcrs and Insects. 149
locked together. The action of the bee, however,
puts an end to this ; the flower explodes, and thus
dusts the bee with pollen.
It would, however, take too long to refer to the
various interesting arrangements by which cross-
fertilisation is secured in this great order of plants.
3. It is, indeed, impossible not to be struck by the
marvellous variety of contrivances found among
flowers, and the light thus thrown upon them, by
the consideration of their relations to insects.
I must now call your attention to certain very
curious cases, in which the same species has two or
more kinds of flowers. Probably in all plants the
flowers differ somewhat in size, and I have already
mentioned some species in which these differences
have given rise to two distinct classes of flowers, one
large and much visited by insects, the other small
and comparatively neglected. In other species — as,
for instance, in some of the Violets — these differ-
ences are carried much further. The smaller flowers
have no smell or honey, the corolla is rudimen-
tary, and, in fact, an ordinary observer would not
recognise them as flowers at all. Such small
flowers are already known to exist in about 50
genera. Their object probably is to secure, with
as little expenditure as possible, the continuance
of the species in cases when, from unfavourable
weather or other causes, insects are absent ; and
under such circumstances, as scent, honey, and
colour would be of no use, it is an advantage to the
1^0 On Flowers and hiseds.
plant to be spared from the effort of their produc-
tion.
4. As the type of another class of cases in which
two kinds of flowers are produced by the same
species (though not on the same stock), we may
take our common Cowslips and Primroses. If you
examine a number of them, you will find that they
fall into two distinct series. In some of the flowers
the pistil is as long as the tube, and the button-
shaped stigma (fig. 53, i-/) is situated at the mouth
of the flower, the stamens {a d) being halfway down
the tube ; while, in the other flowers (fig. 54), on the
contrary, the anthers are at the mouth of the flower,
and the stigma halfway down. The existence of
Fig. 52. — Common Cowslip {Primula va-is).
On Flowers and Insects. 151
these two kinds of flowers had long been known, but
it remained unexplained until Mr. Darwin devoted
his attention to the subject. Now that he has fur-
nished us with the clue, the case is clear enough.
5. An insect visiting a plant of the short-styled
form would dust its proboscis at a certain distance
from the extremity (fig. 54, d), which, when the
insect passed to a long-styled flower, would come
Fig- 53. PoIIea grains. Fig. 54.
Section of the Flower of Section of the Flower ot
Primola. Primula.
Long-styled form. Short-styled form.
just opposite to the pistil (fig. 53, si). At the same
time, the stamens of this second form (fig. 53, d)
would dust the proboscis at a point considerably
nearer to the extremity, which in its turn would
correspond to the position of the stigma in the first
form (fig. 54, s(). The two kinds of flowers never
grow together on the same stock, and the two kinds
of plants generally grow together in nearly equal
Oil Flowers and Insects.
proportions. Owing to this arrangement, therefore,
insects can hardly fail to fertilise each flower with
pollen from a different stock.
6. The two forms differ also in some other
respects. In the long-styled form, the stigma {sf) is
globular and rough, while that of the short-styled
form is smoother and somewhat depressed. These
differences, however, are not sufficiently conspi-
cuous to be shown in the figure. Again, as
shown in the figure, the pollen of the long-styled
form is smaller than the other, a difference the
importance of which is obvious, for each grain of
pollen sends out a tube which penetrates the
whole length of the style, from the stigma to the
base of the flower; and the one has therefore to
produce a tube nearly twice as long as that of the
other. The careful experiments made by Mr.
Darwin have shown that, to obtain the largest
quantity of seed, the flowers must be fertilised by
pollen from the other form. Nay, in some cases,
the flowers produce more seed if fertilised by pollen
from another species, than by that from the other
form of their own.
7. This curious difference in the Primrose and
Cowslip, between flowers of the same species, is
found in most species of the genus Primula, but
not in all.
The Cowslip and Primrose resemble one another
in many respects, but the honey they secrete must
be very different, for while the Cowslip is habitually
On Flowers and Insects. 1 5 3
visited during the day by humble bees, this is not
the case with the Primrose, which appears to be
fertiHsed almost exclusively by moths.
The genus Lythrum affords a still more complex
case, for here we have three forms of flowers. The
stamens are in two groups : in the one form the
pistil projects beyond either of them ; in the second
form it is shorter than either of them, and in the
third it is intermediate in length, so that the stigma
lies between the two sets of anthers.
8. Although flowers present us with these beau-
tiful and complex contrivances, whereby the transfer
of pollen from flower to flower is provided for, and
waste is prevented, yet they appear to be imperfect,
or at least not yet perfect in their adaptations.
Many small insects obtain access to flowers and
rob them of their contents. The Dwarf Mallow
can be, and often is, sucked by bees from the out-
side, in which case the flower derives no advantage
from the visit of the insect. In the Lucerne, also,
insects can suck the honey without effecting fertili-
sation, and the same flower continues to secrete
honey after fertilisation has taken place, and when,
apparently, it can no longer be of any use. Fritz
Miiller has observed that in some plants which are
exclusively fertiHsed by night-flying insects, many
of the flowers nevertheless open in the day, and
consequently remain sterile. It is of course possible
that these cases may be explained away ; neverthe-
less, as both insects and flowers are continually
154
On Flowers and Insects.
altering in their structure, and in their geographical
distribution, we should naturally expect to find
such instances. Water continually tends to find
its own level ; animals and plants as constantly
tend to adapt themselves to their conditions. For
it is obvious that any blossom which differed from
the form and size best adapted to secure the due
transference of the pollen would be less likely to be
fertilised than others ; while, on the other hand,
those richest in honey, sweetest, and most con-
spicuous, would most surely attract the attention
and secure the visits of insects ; and thus, just as
our gardeners, by selecting seed from the most
beautiful varieties, have done so much to adorn our
gardens, so have insects, by fertilising the largest
and most brilliant flowers, contributed uncon-
sciously, but not less effectually, to the beauty oi
our woods and fields.
155
Fig. 5S.— Common Caelina [Carlina vulgaris).
SECTION V.-ON PLANTS AND
INSECTS.
1.
I. In the last chapter I endeavoured to show in
a variety of cases how beautifully flowers are con-
structed, so as to secure their fertilisation by insects.
Indeed, neither plants nor insects would be what
they are, but for the influence which each has
exercised on the other. Some plants, indeed, are
altogether dependent on insects for their very exis-
tence. We know now, for instance, that certain
plants produce no seeds at all, unless visited by
insects. Thus, in some of our colonies, the common
Red Clover sets no seeds on account of the absence
of humble bees ; for the proboscis of the hive bee
is not long enough to effect the object. According
to Mr. Belt, the same is the case, and for the same
reason, in Nicaragua, with the Scarlet-Runner,
156
On Plants and Insects.
But even in those instances in which it is not abso-
lutely necessary, it is an advantage that the flowers
should be fertilised by pollen brought from a dif-
ferent stock, and with this object in view, insects are
tempted to visit flowers for the sake of the honey
and pollen ; while the colours and scents are useful
in making the flowers more easy to find.
2. Fortunately ^for us, bees like the same odours
as we do ; and as the great majority of flowers are
adapted for bees, they are consequently sweet ; but
it might have been otherwise, for flies prefer un-
pleasant smells, such as those of decaying meat,
and other animal substances on which they live as
larva;, and some flowers, consequently, which are
fertilised by them, are characterised by very evil
odours. Colours also are affected in the same
manner, for while bee-flowers (if I may coin such
an expression) have generally bright, clear colours,
fly-flowers are usually reddish or yellowish brown.
The real use of honey now seems so obvious that
it is curious to read the various theories which were
once entertained on the subject.
Sprengel was the first to point out the real office
of honey, but his views were far from meeting with
general assent, and, even as lately as 1833, were
altogether rejected by some naturalists.
3. No doubt, however, seems any longer to exist
that Sprengel's view is right ; and that the true
function of honey is to attract insects, and thus to
secure cross-fertilisation. Thus, most of the Rose
On Plants and Insects.
157
family are fertilised by insects, and possess nec-
taries ; but, as Delpino has pointed out, the connmon
Burnet is wind-fertilised, and possesses no honey.
So also the Maples are almost all fertilised by in-
sects, and produce honey ; but some kinds are
wind-fertilised and honeyless. Again, among the
Polygonums, some species are insect-fertilised and
honey-bearing ; while, on the other hand, the Docks
and some others have no honey, and are fertilised
by the wind. At first sight it might appear an
objection to this view — and one reason, perhaps,
why the earlier botanists missed the true use of
honey may have been the fact — that some plants
(as, for instance, the Common Laurel) secrete
honey on other parts than the flowers.
4. Belt and Delpino have, I think, suggested the
true function of these extra-floral nectaries.* The
former of these excellent observers describes a
South American species of Acacia: this tree, if
unprotected, is apt to be stripped of the leaves by
a leaf-cutting ant, which uses them, not directly for
food, but, according to Mr. Belt, to grow mush-
rooms on. The Acacia, however, bears hollow
thorns, while each leaflet produces honey in a
crater-formed gland at the base, and a small, sweet,
pear-shaped body at the tip. In consequence, it is
inhabited by myriads of a small ant, which nest in
* I by no means, however, wish to suggest that we as yet fully
understand the facts. For instance, the use of the nectary at the
base of the leaf of the fern is still quite unexplained.
158
Ott Plants and Insects.
the hollow thorns, and thus find meat, drink, and
lodging all provided for them. These ants are conti-
nually roaming over the plant, and constitute a most
efficient body-guard, not only driving off the leaf-
cuttingants, but, in Belt's opinion, renderingthe leaves
less liable to be eaten by herbivorous mammalia.
5. I am not aware that any of our English plants
are protected in this manner from browsing quad-
rupeds, but not the less do our ants perform for
them a very similar function, by keeping down the
number of small insects, which would otherwise rob
them of their sap and strip them of their leaves.
Forel watched, from this point of view, a nest of
ants. He found that they brought in dead insects,
small caterpillars, grasshoppers, cercopis, &c., at
the rate of about 28 a minute, or more than 1600
in an hour. When it is considered that the ants
work, not only all day, but in warm weather, often
all night too, it is easy to see how important a
function they fulfil in keeping down the number of
small insects.
6. Some of the most mischievous insects, indeed
— certain species, for instance, of green fly and scale
insect — have turned the tables on the plants, and
converted ants from enemies into friends, by them-
selves developing nectaries and secreting honey,
which the ants love. We have all seen the little
brown Garden Ant, for instance, assiduously run-
ning up the stems of plants, to milk their curious
little cattle. In this manner, not only do the
On Plants and Insects.
159
aphides and cocci secure immunity from the attacks
of the ants, but even turn them from foes into
friends. They are subject to the attacks of a
species of ichneumon, which lays its eggs in them ;
and Delpino has seen ants watching over the scale
insects with truly maternal vigilance, and driving
off the ichneumons whenever they attempted to
approach.
7. But though ants are in some respects very
useful to plants, they are not wanted in the flowers.
The great object is to secure cross-fertilisation ; but
for this purpose winged insects are almost necessary,
because they fly readily from one plant to another,
and generally, as already mentioned, confine them-
selves for a certain time to the same species.
Creeping insects, on the other hand, naturally would
pass from each floret to the next ; and it is of little
use to bring pollen from a different flower of the
same stock; it must be from a different plant alto-
gether. Moreover, creeping insects, in quitting a
1" plant, would generally go up another close by, with-
out any regard to species. Hence, even to small
■ flowers, which, as far as size is concerned, might
well be fertilised by ants, the visits of flying insects
are much more advantageous. Moreover, if larger
flowers were visited by ants, not only would these
deprive the flowers of their honey, without fulfilling
any useful function in return, but they would pro-
bably prevent the really useful visits of bees. If
you touch an ant with a needle or a bristle, she is
i6o On Plants and Insects.
almost sure to seize it in her jaws ; and if bees,
when visiting any particular flowers, were liable to
have the delicate tip of their proboscis seized on by
the horny jaws of an ant, we may be sure that such
a plant would soon be deserted.
8. On the other hand, we know how fond ants
are of honey, and how zealously and unremittingly
they search for food. How is it, then, that they do
not anticipate the bees, and secure the honey for
themselves } Kerner has recently published a most
interesting book on this subject, and has pointed
out a number of ingenious contrivances by which
flowers protect themselves from the unwelcome
visits of such intruders. The most frequent are
the interposition of thick hedges, as it were, in the
shape of hairs, which ants cannot penetrate, glu-
tinous parts which they cannot traverse, slipper}^
slopes which they cannot climb, or barriers which
close the way.
9. Firstly, then, as regards these hairs. In some
respects these are the most effectual protection,
since they exclude not only creeping insects, but
also other creatures, such as slugs. With this
object, it will be observed that the hairs which
cover the stalks of so many herbs usually point
downwards. A good example of this is afforded,
for instance, by a plant (fig. 56) allied to our common
Blue Scabious. The heads of the common Carline
(fig. 55), again present a sort of thicket, which must
offer an almost impenetrable barrier to ants. Some
On Plants and Insects.
l6i
species of plants, on the other hand, are quite
smooth, excepting just below the flowers. The
common but beautiful Cornflower is quite smooth,
but the flower-head is bordered with recurved teeth.
In this case, neither the stem nor the leaves show a
trace of such prickles.
Fig. 56. — Knaidia dipsacifolia
l62
On Plants and Insects.
Fig. 57. — Amphibious Polygonum {Polygonum amphibiuin),
II.
I. The same consideration throws light on the
large number of plants which are more or less
glutinous, a condition generally produced — as, for
instance, in the flowers of the Gooseberry and
of Linnaea borealis (fig. 58) — by the presence of
glandular hairs. Kerner has called attention to a
very interesting illustration afforded by a kind of
Polygonum (fig. 57). In this species the stigma,
or top of the pistil, projects about one-fifth of an
inch above the flower, so that if ants could obtain
access, they would steal the honey without ferti-
lising the flower ; a flying insect, on the contrary^
Oil Plants and Insects.
aliehtine on the flower, could scarcely fail to touch
the stigma.
2. The flowers of this species are of a beautiful
rosy colour, and are rich in nectar ; the stamens are
short ; the pistil, on the contrary, projects consider-
ably above the corolla. The nectar is not protected
by any special arrangement of the flower itself, and
is accessible even to very small insects. The sta-
mens ripen before the pistil, and any flying insect,
however small, coming from above, would assist in
Fig. 58. — LiNN/EA.
cross-fertilisation. Creeping insects, on the con-
trary, which in most cases would enter from below,
would rob the honey without benefiting the plant.
The Amphibious Polygonum, as its name denotes,
grows sometimes in water, sometimes on land. So
long, of course, as it grows in water, it is thoroughly
protected, and then the stem is smooth ; while, on
the other hand, those specimens which live on land
throw out certain hairs which terminate in sticky
glands, and thus prevent small insects from creep-
ing up to the flowers. In this case, therefore, the
M 2
164
On Plants and Insects.
plant is not sticky, except just when this condition
is useful. All these viscous plants, as far as I
know, have upright or horizontal flowers.
3. On the other hand, where the same object is
effected by slippery surfaces, the flowers are often
hanging ; creeping creatures being thus kept out of
them, just as the hanging nests of the weaver-bird
are a protection from snakes and other enemies.
As instances of this kind I may mention the
common Snowdrop and the Cyclamen.
Many flowers close their petals during rain, and
this is obviously an advantage, since it prevents
the honey and pollen from being spoilt or washed
away. I have elsewhere suggested that the so-called
" sleep" of flowers has reference to the habits of
insects, on the ground that flowers which are fer-
tilised by night-flying insects would derive no
advantage from being open in the day ; while, on
the other hand, those which are fertilised by bees
would gain nothing by being open at night.
4. The Nottingham Catchfly (fig. 59) is a very
instructive species from this point of view, and
indeed illustrates a number of interesting points in
the relations between plants and insects. The
upper part of the flowering stem is viscid, from
which it has derived its English name, the Notting-
ham Catchfly. This prevents the access of ants
and other small creeping insects. Each flower
lasts three days, or rather three nights. The sta-
mens are 10 in number, arranged in two sets, the
On Plants mid Insects.
165
one set standing in front of the sepals, the other
in front of the petals. Like other night flowers, it
is white, and opens towards evening, when it also
becomes extremely fragrant. The first evening,
towards dusk, the five stamens in front of the sepals
(fig. 60) grow very rapidly for about two hours, so
Fig- S9-— Nottingham Catchfly {Silene nutans).
that they emerge from the flower; the pollen ripens,
and is exposed by the bursting of the anther. So
the flower remains through the night, very attractive
to, and much visited by, moths. Towards three in
the morning the scent ceases, the anthers begin to
shrivel up or drop off, the filaments turn themselves
outwards, so as to be out of the way, while the
1 66 On Plants and Insects.
petals, on the contrary, begin to roll themselves
up, so that by daylight they close the aperture of
the flower, and present only their brownish-green
undersides to view ; which, moreover, are thrown
into numerous wrinkles. Thus, by the morning's
light, the flower has all the appearance of being
faded. It has no smell, and the honey is covered
over by the petals. So it remains all day. Towards
evening, how^ever, everything is changed. The
petals unfold themselves ; by eight o'clock the
flower is as fragrant as before, the second set of
Fig. 60. — Nottingham Catchfly {SUene nutans).
Stamens have rapidly grown, their anthers are
open, and the pollen again exposed. By morning
the flower is again " asleep," the anthers are
shrivelled, the scent has ceased, and the petals
rolled up as before. The third evening, again the
same process occurs, but this time it is the pistil
which grows ; the long spiral stigmas on the third
evening take the position which on the previous
two had been occupied by the anthers, and can
hardly fail to be dusted by moths with pollen
brought from another flower.
On Plants and Insects. 167
5. An objection to the view that the sleep of
flowers is regulated by the visits of insects, might be
derived from the cases of those flowers which close
early in the day, the well-known Yellow Goats'-
beard, or "John Go-to-bed-at-Noon" (fig. 61), for
instance; still more such species as the Nipplewort
or the smooth Crepis, which open before six and
Fig. 61. — ^JOHN GO-TO-BED-AT-NoON, Or GOATS'-BEARU
( Tragopogoit pratensc).
close again before ten in the morning. Bees, however,
are very early risers, while ants come out later,
when the dew is off ; so that it might be an advan-
tage to a flower which was quite unprotected, to
open early for the bees, and close again before the
ants were out, thus preserving its honey exclusively
for bees.
Fig. 62. — Valisneria.
«, pislillote flower; b, staminate flower ; floating pollen.
169
SECTION VI.-FRUITS AND SEEDS.
I.
I, Though technical terms are very necessary in
science, I shall endeavour, as far as I can, to avoid
them here. As, however, it will be impossible for
me to do so altogether, I will do my best at the
commencement to make them as clear as possible.
In order to understand the structure of the seed,
we must commence with the flower, to which the
seed owes its origin. Now, if you take such a
flower as, say a Geranium, you will find, as has
been already explained, that it consists of the
following parts: — Firstly, there is a whorl of green
leaves, known as the sepals, and together forming
the calyx ; secondly, a whorl of coloured leaves,
or petals, generally forming the most conspicuous
part of the flower, and called the corolla ; thirdly,
a whorl of organs more or less like pins, which are
called stamens ; and in the heads, or anthers, of
which the pollen is produced. These anthers are
in reality modified leaves ; in the so-called double
flowers, as, for instance, in our Garden Roses,
they are developed into coloured leaves like those
Fnciis and Seeds.
of the corolla, and monstrous flowers are not
unfrequently met with, in which the stamens are
green leaves, more or less resembling the ordinary
leaves of the plant. Lastly, in the centre of the
flower is the pistil, which also is theoretically to be
considered as constituted of one or more leaves,
each of which is folded on itself, and called a carpel.
Sometimes there is only one carpel. Generally the
carpels have so completely lost the appearance of
leaves, that this explanation of their true nature
requires a considerable amount of faith. The base
of the pistil is the ovary, composed, as I have just
mentioned, of one or more carpels, in which the
seeds are developed. I need hardly say that many
so-called seeds are really fruits ; that is to say, they
are seeds with more or less complex envelopes.
2. We all know that seeds and fruits differ greatly
in different species. Some are large, some small ;
some are sweet, some bitter ; some are brightly —
some dull — coloured, some are good to eat, some
poisonous ; some spherical, some winged ; some
covered with bristles, some with hairs ; some are
smooth, and some very sticky.
We may be sure that there are good reasons for
these differences.
3. In the first place, then, during growth, seeds in
many cases require protection. This is especially
the case with those of an albuminous character. It
is curious that so many of those which are luscious
when ripe, as the Peach, Strawberry, Cherrj'.
Fruits and Seeds.
171
Apple, &c., are stringy, and almost inedible, till ripe.
Moreover, in these cases, the fleshy portion is not
the seed itself, but only the envelope, so that even
if the sweet part is eaten the seed itself remains
uninjured.
4. On the other hand, such seeds as the Hazel,
Beech, Spanish Chestnut, and innumerable others
are protected by a thick, impervious shell, which is
especially developed in the Brazil-nut, the so-called
Monkey Pot, the Cocoa-nut, and other plants.
In other cases the envelopes protect the seeds,
not only by their thickness and toughness, but also
by their bitter taste, as, for instance, in the Walnut.
One genus {Mucund) is remarkable in having the
pods covered with stinging hairs.
5. In many cases the calyx, which is closed when
the flower is in bud, opens when the flower ex-
pands ; and then, after the petals have fallen, closes
again until the seeds are ripe, when it opens for the
second time. This is, for instance, the case with
the common Herb Robert (fig. 68). In a South
European plant allied to the thistles the outer
envelopes form an exquisite little cage. Another
case, perhaps, is that of Nigella, or, as it is seme-
times more prettily called, " Love-in-a-Mist," of
old English gardens.
6. Again, the protection of the seed is in many
cases attained by curious movements of the plant
itself. In fact, plants move much more than is
generally supposed. So far from being motionless,
172
Frtiiis and Seeds.
they may almost be said to be in perpetual move-
ment, though the changes of position are generally
so slow that they do not attract attention. This is
not, however, always the case. We are all familiar
with the Sensitive Plant, which droops its leaves
when touched. Another species has leaves like
those of an Acacia, and all day the leaflets go
slowly up and down. There is a sort of pea living
in India which has trifoliate leaves, the lateral leaf-
lets being small and narrow ; and these leaflets are
perpetually moving round and round, whence the
specific name gyi^ans. In this case the object of
the movement is quite unknown to us. In Dioncea,
as already mentioned (p. 116), the leaves form a
regular fly-trap. Directly an insect alights on them
they shut up with a snap.
7. In a great many cases leaves are said to sleep —
that is to say, at the approach of night they change
their position, and sometimes fold themselves up,
thus presenting a smaller surface for radiation, and
being, in consequence, less exposed to cold. Mr.
Darwin has proved experimentally that leaves
which were prevented from moving suffered more
from cold than those which were allowed to assume
their natural position. He has observed with re-
ference to the arrowroot plant that, if it has had a
severe shock, it cannot get to sleep for the next
two or three nights.
8. The sleep of flowers is also probably a case of
the same kind. These motions, indeed, have but
Fruits and Seeds.
1/3
an indirect reference to our present subject. On
the other hand, in the Dandelion the flower-stalk is
upright while the flower is expanded, a period
which lasts for three or four days ; it then lowers
itself, and lies close to the ground for about twelve
days while the fruits are ripening, and then rises
again when they are mature. In the Cyclamen the
stalk curls itself up into a beautiful spiral after the
flower has faded.
The flower of the little Linaria of our walls
pushes out into the light and sunshine, but as soon
as it is fertilised it turns round and endeavours to
find some hole or cranny in which it may remain
safely ensconced until the seed is ripe.
9. In some water-plants the flower expands at the
surface, but after it is faded retreats again to the
bottom. This is the case, for instance, with the
Water Lilies and several other aquatic plants. In
Valisneria, again, as already mentioned, the pistil-
late flowers (fig. 62, a) are borne on long stalks,
which reach to the surface of the water, on which the
flowers float. The staminate flowers (fig. 62, b), on
the contrary, have short straight stalks, from which,
when mature, the pollen (fig. 62, c) detaches itself,
rises to the surface, and, floating freely on it, is
wafted about, so that it comes in contact with the
pistillate flowers. After fertilisation, however, the
long stalk coils up spirally, and thus carries the
ovary down to the bottom, where the seeds can
ripen in greater safety.
174
Fruits and Seeds.
Fig. 63. — Hairy Bittercress {Cardamine hirsuta).
II.
I. The next points to which I will direct your at-
tention are the means of dispersion possessed by-
many seeds. Farmers have found by experience
that it is not desirable to grow the same crop in the
same field year after year, because the soil becomes
more or less exhausted. In this respect therefore
the powers of dispersion possessed by many seeds
are a great advantage to the species. Moreover,
they are also advantageous in giving the seed a
chance of germinating in new localities suitable to
the requirements of the species. Thus, one com-
Fruits and Seeds.
175
mon European species has rapidly spread over the
whole of South Africa, the seeds, which are covered
with hooked spines, being carried in the wool of
sheep.
2. There are a great many cases in which plants
possess powers of movement directed to the dis-
semination of the seed. Thus, there are some
funguses which grow underground, but eventually
come up to the surface of the ground, split open
and shed their spores* in the form of dust.
I have already referred to the case of the common
Dandelion. Some plants, as we .shall see, even
sow their seeds in the ground, but these cases will
be referred to later on.
3. In other cases the plant throws its own seeds
to some little distance. This is the case with the
common Hairy Bittercress (fig. 63), a little plant, I
do not like to call it a weed, six or eight inches
high, which comes up abundantly on any vacant
spot in our kitchen gardens or shrubberies. The
seeds are contained in a pod which consists of three
parts, a central membrane and two side walls.
When the pod is ripe the walls are much stretched.
The seeds are loosely attached to the central piece
by short stalks. Now, when the proper moment
has arrived, the outer walls are kept in palace by a
delicate membrane only just strong enough to
* These are tiny seed-like bodies, but are termed " spores " by
botanists, because in some important points they differ from true
seeds.
176
Fruits and Seeds.
resist the tension. The least touch, for instance a
puff of wind blowing the plant against a neighbour,
detaches the outer wall, which suddenly rolls itself
up, generally with such force as to fly from the
plant, thus jerking the seeds to a distance of
several feet.
4. In the common Violets, besides the coloured
flowers, there are others in which the corolla is
either absent or imperfectly developed. The sta-
mens also are small, but contain pollen, though less
than in the coloured flowers. In the autumn large
numbers of these curious flowers are produced.
When very young they look like an ordinary
flower-bud (fig. 64, d), the central part of the
flower being entirely covered by the sepals, and
the whole having a triangular form. When older
(figs. 64 and 65, b) they look at first sight like an
ordinary seed capsule, so that the bud seems to
pass into the capsule without the flower stage.
The Pansy Violets do not possess these interesting
flowers. In the Sweet Violet and Hairy Violet
(fig. 64) they may easily be found by searching
among the leaves nestling close to the ground. It
is often said that the plants actually force these
capsules into the ground, and thus sow their own
seeds. I have not, however, found this to be the
case ; though, as the stalk lengthens, and the point
of the capsule turns downwards, if the earth be
loose and uneven, it will no doubt sometimes so
Fruits and Seeds.
•77
happen. When the seeds are fully ripe the capsule
opens by three valves and allows them to escape.
Fig. 64.— Hairy Violet {Viola hirta).
a, young bud ; b, ripe seed capsule.
5. In the Dog Violet (fig. 65) the case is very
different. The capsules are less fleshy, and, though
hanging down when young, at maturity they erect
themselves (fig. 65, c), stand up boldly above the
N
1/8
Fruits and Seeds.
Fig. 66.— Dog Violet. Seed-vessel open and showing seeds.
Fruits mid Seeds.
1/9
rest of the plant, and open by the three equal
valves (fig. 66), resembling an inverted tripod.
Each valve contains a row of three, four, or five
brown, smooth, pear-shaped seeds, slightly flattened
at the upper, wider end. Now the two walls of
each valve, as they become drier, contract, and so
approach one another, thus tending to squeeze out
the seeds. These resist some time ; but at length
lr|g. 57. — Dog Violet. Seed-vessel after ejecting the seeds.
the attachment of the seed to its base gives way,
and it is ejected several feet, this being no doubt
much facilitated by its form and smoothness. I
have known even a gathered specimen throw a
seed nearly 10 feet. Fig. 67 represents a capsule
after the seeds have been ejected.
6. Now we naturally ask ourselves what is the
reason for this difference between the species of
violets ; why does the Sweet Violet conceal its cap-
N 2
Fruits and Seeds.
sules among the moss and leaves on the ground,
while the Dog Violet and others raise theirs boldly
above their heads and throw the seeds to seek their
fortune in the world ? If this arrangement be best
for the Dog Violet, why has not the Sweet Violet
also adopted it? The reason is, I beheve, to be
found in the different mode of growth of these two
species. The Dog Violet is a plant with an elon-
gated stalk, and it is easy therefore for the capsule
to raise itself above the grass and other low herbage
among which violets grow. The Sweet Violet, on
the contrary, has, in ordinary parlance, no stalk,
and the leaves are radical, i.e., rising from the root.
This is at least the case apparently, though, botani-
cally speaking, they rise at the end of a short
stalk. Now, under these circumstances, if the
Sweet Violet attempted to shoot its seeds, the cap-
sule not being sufficiently elevated, the seeds would
merely strike against some neighbouring leaf, and
immediately fall to the ground. Hence, I think,
we see that the arrangement of the capsule in each
species is that which is most suitable to the general
habit of the plant.
Fruits and Seeds. 1 8 1
Fig. 68. — Herb-Robert Geranium {Geranium Roberiianum).
a, bud ; b, flower ; c, flower after the petals have fallen ; </, flower
with seeds nearly ripe ; e, flower with ripe seeds ; f, flower after
throwing seeds.
III.
I. In the true Geraniums again, as for instance, in
the Herb Robert (fig. 68), after the flower has faded,
l82
Friiiis and Seeds.
the central axis gradually lengthens (fig. 68, c d).
The seeds, five in number, are situated at the base
of the column, each being enclosed in a capsule,
which terminates upwards in a rod-Hke portion,
which at first forms part of the central axis, but
gradually detaches itself When the seeds are ripe
the ovary raises itself into an upright position (fig.
68, e) ; the outer layers of the rod-like termination
of the seed-capsule come to be in a state of great
tension, and eventually (fig. 70) detach the rod with
a jerk, and thus throw the seed some little distance.
Fig. 68, f, represents the central rod after the seeds
have been thrown. In some species, as for instance
in the Cut-leaved Geranium (fig. 69), the capsule-
rod remains attached to the central column and the
seed only is ejected,
2. It will, however, be remembered that the cap-
sule is, as already observed, a leaf folded on itself,
with the edges inwards, and in fact, in the Geranium,
the seed-chamber opens on its inner side. You will,
therefore, naturally observe to me that when the
carpel bursts outwards, the only effect would be
that the seed would be forced against the outer
wall of the carpel, and that it would not be ejected,
Decause the opening is not on the outer but on the
inner side. Your remark is perfectly just, but the
difficulty has been foreseen by our Geraniums, and
is overcome by them in different ways. In some
species, as for instance in the Cut-leaved Geranium,
a short time before the opening of the pods, the
Fruits and Seeds.
183
seed-chamber places itself at right angles to the
pillar (fig. 69, a\ The edges then separate, but they
are provided with a fringe of hairs, just strong
enough to retain the seed in its position, yet suffici-
ently elastic to allow it to escape when the carpels
Fig. 6g. — The Cut-leaved Geranium.
jiist before throwing seed ; just after throwing seed ; c, the
capsule still attached to the rod ; d, the seed.
burst away, remaining attached, however, to the
central pillar by their upper ends (fig. 69, c).
3. In the common Herb Robert (fig. 68 and 70),
and some other species, the arrangement is somewhat
different. In the first place the whole carpel springs
Fruits and Seeds.
away (fig. 70, b and c). The seed-chamber (fig. 70,
c) detaches itself from the rod of the carpel (fig. 70,
b), and when the seed is flung away remains
attached to it. Under these circumstances it is
Diagram.
Fig. 70. — Herb Robert.
a, just before throwing the seed ; b, the rod ; i", the seed
enclosed in the capsule.
unnecessary for the chamber to raise itself from the
central pillar, to which accordingly it remains close
until the moment of disruption (fig. 70, a). The
seed-chamber is moreover held in place by a short
tongue which projects a little way over its base ;
Fruits and Seeds.
185
while, on the other hand, the lower end of the rod
passes for a short distance between the seed-capsule
and the central pillar. The seed-capsule has also
near its apex a curious tuft of silky hair (fig. 70, c),
the use of which I will not here stop to discuss.
As the result of all this complex mechanism the
seeds when ripe are flung to a distance which is
Fig. 71. — Wood Vetch ( Vicia sylvatica).
surprising when we consider how small the spring
is. In their natural abode it is almost impossible
to find the seeds when once thrown. I therefore
brought some into the house and placed them on
my billiard table. They were thrown from one
end completely over the other, in some cases more
than 20 feet.
4. Some species of Vetch (fig. 71), again, and the
i86
Fruits and Seeds.
common Broom, throw their seeds, owing to the
elasticity of the pods, which, when ripe, open sud-
denly with a jerk. Each valve of the pod contains
a layer of woody cells, which, however, do not pass
straight up the pod, but are more or less inclined
to its axis (fig. 72}. Consequently, when the pod
Fig. 72. — Pod of the Bush Vetch,
The line a b sliows the direction of the woody fibres.
bursts it does not, as in the case of the Bittercress,
roll up like a watch-spring, but twists itself more
or less like a corkscrew.
5. I have mentioned these species because they are
some of our commonest wild flowers, so that during
the summer and autumn we may, in almost any
walk, observe for ourselves this innocent artillery.
Fruits and Seeds.
187
There are, however, many other more or less similar
cases. Thus the Squirting Cucumber, a common
plant in the south of Europe, and one grown in
some places for medicinal purposes, effects the same
object by a totally different mechanical arrange-
ment. The fruit is a small cucumber (fig. 73), and
when ripe it becomes so gorged with fluid that it is
Fig. 73.— Fniit of the SQUIRTING CUCUMBER.
in a state of great tension. In this condition a very
slight touch is sufficient to detach it from the stalk,
when the pressure of the walls ejects the contents,
throwing the seed some distance. In this case of
course the contents are ejected at the end by which
the cucumber is attached to the stalk. If any one
i88
Fruits and Seeds.
touches one of these ripe fruits, they are often
thrown with such force as to strike him in the face.
6. Even those species which do not eject their
seeds often have them so placed with reference to the
capsule that they only leave it if swung or jerked
by a high wind. In the case of trees, "even seeds
with no special adaptation for dispersion must in
this manner be often carried to no little distance ;
and to a certain, though less extent, this must hold
good even with herbaceous plants. It throws light
on the fact that in so many plants with small, heavy
Fig. 74. — Poppy-head.
Fruits and Seeds.
seeds, the capsules open, not at the bottom, as
one might perhaps have been disposed to expect,
but at the top. A good illustration is afforded
by the well-known case of the common Poppy
(fig. 74), in which the upper part of the capsule
presents a series of little doors (fig. 74, a), through
which, when the plant is swung by the wind,
the seeds come out one by one. The little doors
are protected from rain by overhanging eaves,
and are even said to shut of themselves in wet
weather. The Bellflowers {Cainpaindd) are also
interesting from this point of view, because some
species have the capsules pendent, some upright,
and those which are upright open at the top, while
those which are pendent do so at the base.
190
',1
Fruiis and Seeds.
IV.
1. In other cases the dispersion is mainly the
work of the seed itself. In some of the lower plants,
as, for instance, in many seaweeds, and in some
fresh-water plants allied to them, the spores* are
covered by vibratile hairs, and actually swim about
in the water, like microscopic animals, till they have
found a suitable spot on which to grow. Nay, so
much do the spores of some seaweeds resemble
animals, that they are provided with a red " eye-
spot" as it has been called, which, at any rate,
seems so far to deserve the name that it appears to
be sensitive to light. This mode of progression is,
however, only suitable to water plants. One group
of small, low-organized plants develops among the
spores a number of cells with spirally thickened
walls, which, by their contractility, are supposed
to disseminate the spores.
2. In much more numerous cases, seeds are carried
by the wind. For this of course it is desirable that
they should be light. Sometimes this object is
attained by the character of the tissues themselves,
sometimes by the presence of empty spaces. Thus,
* Speaking botanically, these are not true seeds, but rather moving
buds.
Fntits and Seeds.
in the Lamb's Lettuce,* the fruit contains three
cells, each of which would naturally be expected to
contain a seed. One seed only, however, is deve-
loped, but the two cells which contain no seed
actually become larger than the one which alone
might, at first sight, seem to be normally developed.
We may be sure from this that they must be of some
use, and, from their lightness, they probably enable
the wind to carry the seed to a greater distance
than would otherwise be the case.
3. In other instances the plants themselves, or
parts of them, are rolled along the ground by the
wind. An example of this is afforded, for instance,
by a kind of Australian grass, in which the mass of
flowers, forming a large round head, is thus driven
for miles over the dry sands until it comes to a
damp place, when it expands and soon strikes root.
So, again, the " Rose of Jericho," a small annual
with rounded pods, which frequents sandy places in
Egypt, Syria, and Arabia, when dry, curls itself up
into a ball or round cushion, and is thus driven
about by the wind until it finds a damp place,
when it uncurls, the pods open, and sow the seeds.
4. These cases, however, in which seeds are rolled
by the wind along the ground are comparatively
rare. There are many more in which seeds are
wafted through the air. If you examine the fruit
of a Sycamore, you will find that it is provided with
a wing-like expansion, in consequence of which, if
* Valerianella.
192
Fruits and Seeds.
a
Fig- 75-
Seeds or Frtiils.
a, maple ; l>, sycamore ; c, lime ; d, hornbeam ; e, elm ;
f, birch ; g, pine ; h, fir ; i, ash.
Fruits and Seeds.
193
there is any wind when it falls, it is, though rather
heavy, blown to some distance from the parent tree.
Several cases are shown in fig. 75 ; for instance, the
Maple {d), Sycamore {b), Hornbeam {d), Elm {e),
Birch (/), Pine {g), Fir {h), and Ash (z), while in
the Lime (c) the whole bunch of fruits drops toge-
ther, and the " bract," as it is called, or leaf of the
flower-stalk, serves the same purpose.
In a great many other plants the same result is
obtained by flattened and expanded edges. Among
our common wild plants we find winged fruits in
the Dock (fig. 27) and in the common Parsnip. But
though in these cases the object to be obtained — •
namely, the dispersion of the seed — is efifected in a
similar manner, there are differences which might
not at first be suspected. Thus in some cases, as,
for instance, in the Pine, it is the seed itself which is
winged ; in Thlaspi arvense it is the pod ; in one*
leguminous plant the pod breaks up into segments,
each of which is winged ; in anotherf the extremity
of the pod is expanded into a flattened wing ; lastly,
in the Lime (fig. 75), as already mentioned, the
fruits drop off in a bunch, and the leaf at the base
of the common flower-stalk, or " bract," as it is
called, forms the wing.
6. Another mode, which is frequently adopted, is
the development of long hairs. Sometimes, as in
Clematis and Anemone, these hairs take the form
of a long feathery awn. In others the hairs form
* Entada. f Nissolia.
O
194
Friuu a7id Seeds.
a tuft or crown, which botanists term a "pappus."
Of this the Dandelion and John Go-to-Bed-at-
Noon, so called from its habit of shutting its flowers
about mid-day, are well-knov/n examples. Tufts of
hairs, which are themselves sometimes feathered, are
developed in a great many flowers allied to the
Dandelion, though some — as, for instance, the Daisy
and Lapsana— are without them ; in some very
interesting species, of which the common Hawkbit
of our lawns and meadows is an example, there are
two kinds of fruits, as shown in fig. 76, b, one with
a pappus and one without. The former are adapted
to seek " fresh fields and pastures new," while the
latter stay and perpetuate the race at home.
7. A more or less similar pappus is found among
various English plants — in the Willow Herb (figs.
28 and 76, d), Hawkbit (fig. 76, U), Tamarix (fig.
76, c), Willow (fig. 76, d\ Cotton Grass (fig. 76, i),
and Bullrush (fig. 76,/); while in exotic species
there are many other cases — as, for instance, the
beautiful Oleander. As in the wings, so also in
that of the pappus, it is by no means always the
same part of the plant which develops into the
crown of hairs.
8. In other cases seeds are wafted by water. Of
this the Cocoa-nut is one of the most striking
examples. The seeds retain their vitality for a
considerable time, and the loose texture of the
husk protects them and makes them float. Every
one knows that the Cocoa-nut is one of the first
Fruits and Seeds.
195
Fig. 76.
Seeds or Fruits.
a, willow herb {Epilobium) ; b, two forms of seed of hawkbil ;
c, tamarix ; d, willow {Salix) ; e, cotton grass [Eriophoruni] ;
, f, bullrush ( Typha).
0 2
196
Fruits, and Seeds.
plants to make its appearance on coral islands, and
it is, I believe, the only palm which is common to
both hemispheres.
The seeds of the common Duckweeds (fig. 77)
sink to the bottom of the water in autumn, and
remain there throughout the winter ; but in the
spring they rise up to the surface again and begin
to grow.
9. In a veiy large number of cases the diffusion
of seeds is effected by animals. To this class belong
the fruits and berries. In them an outer fleshy
Fig. 77. — Lesser Duckweed {Lei/ma niinor).
portion becomes pulpy, and generally sweet, enclo-
sing the seeds. It is remarkable that such fruits,
in order, doubtless, to attract animals, are, like
flowers, brightly coloured — as, for instance, the
Cherry, Currant, Apple, Peach, Plum, Strawberry,
Raspberry, and many others. This colour, more-
over, is not present in the unripe fruit, but is rapidly
developed at maturity. In such cases the actual
seed is generally protected by a dense, sometimes
almost stony, covering, so that it escapes digestion,
while its germination is perhaps hastened by the
Fruits and Seeds.
197
heat of the animal's body. It may be said that
the skin of apple and pear pips is comparatively
soft ; but then they are embedded in a stringy core,
which is seldom eaten.
These coloured fruits form a considerable part of
the food of monkeys in the tropical regions of the
earth, and we can, I think, hardly doubt that these
animals are guided by the colours, just as we are,
in selecting the ripe fruit.
10. In these instances of coloured fruits, the fleshy
edible part more or less surrounds the true seeds ;
in others the actual seeds themselves become edible.
In the former the edible part serves as a temptation
to animals ; in the latter it is stored up for the use
of the plant itself. When, therefore, the seeds
themselves are edible they are generally protected
by more or less hard or bitter envelopes, for
instance the Horse Chestnut, Beech, Spanish
Chestnut, Walnut, &c. That these seeds are used
as food by squirrels and other animals is, however,
by no means necessarily an evil to the plant, for the
result is that they are often carried some distance
and then dropped, or stored up and forgotten, so
that, by this means, they get carried away from the
parent tree.
11. In another class of instances, animals, uncon-
sciously or unwillingly, serve in the dispersion of
seeds. These cases may be divided into two
classes, those in which the fruits are provided with
hooks, and those in which they are sticky. To the
Fruks and Seeds.
f
Fig. T^.
Seeds or Fruits.
a, burdock (Lappa) ; d, agrimony [Agrimonia) ; c, bur parsley
(Caticalis) ; d, enchanter's nightshade [Circcea] ; e, cleavers
{Galium); f, forget-me-not [Myosolis).
Fruits and Seeds.
Fig. 79.
Frtiits.
a, Harpas^ophyion procwnhens (natural size) ; b, Martynia
proboscidca (natural size).
200
Fruits and Seeds.
first class belong, among our common English plants
the Burdock (fig. 78, a) ; Agrimony (fig. 78, b) ; the
Bur Parsley (fig. 78, c); Enchanter's Nightshade
(fig. 78, d)\ Goose Grass or Cleavers (fig. 78, e);
and some of the Forget-me-nots (fig. 78,/). The
hooks, moreover, are so arranged as to promote the
removal of the fruits. In all these species the hooks,
though beautifully formed, are small ; but in some
foreign species they become truly formidable. Two
of the most remarkable are represented above,—
Martjmia proboscidea (fig. 79, b) and Harpagophyton
procnmbetis (fig. 79, d). Martynia is a plant of
Louisiana, and if its fruits once get hold of an
animal it is most difficult to remove them. Har-
pagophyton is a South African genus. The fruits
are most formidable, and are said sometimes even
to kill lions. They roll about over the dry plains,
and if they attach themselves to the skin, the
wretched animal tries to tear them out, and some-
times getting them into its mouth perishes miserably.
Fruits and Seeds. 20 r
V.
1. The cases in which the diffusion of fruits and
seeds is effected by their being sticky are less
numerous, and we have no well-marked instance
among our native plants. The common Plumbago
of South Europe is a well-marked case. There are
comparatively few cases in which the same plant
uses more than one of these modes of promoting
the dispersion of its seeds, still there are some such
instances. Thus, in the common Burdock the seeds
have a pappus, while the whole flower-head is pro-
vided with hooks which readily attach themselves
to any passing animal.
2. But perhaps it will be said that I have picked
out special cases ; that others could have been
selected which would not bear out, or perhaps
would even negative, the inferences which have
been indicated; that I have put "the cart before the
horse ; " that the Ash fruit has not a wing in order
that it may be carried by the wind, nor the Burdock
hooks that the heads may be transported by ani-
mals, but that, happening to have wings and hooks,
these seeds are thus transported. Now, doubtless
there are many points connected with seeds which
are as yet unexplained ; in fact, it is partly because
202 Fruiti and Seeds'.
this is so that I have been anxious to direct atten-
tion to the subject. Still, I believe the general
explanations which have been given by botanists
will stand any test.
3. Let us take, for instance, seeds formed on
the same type as that of the Ash — heavy fruits,
with a long wing. Now, such d, fruit would be
of little use to low herbs. If, however, the wing
was accidental — if it were not developed to serve
as a means of dispersion — it would be as likely
to occur on low plants and shrubs as on trees.
Let us, then, consider on what kind of plants these
fruits are found. They occur on the Ash, Maple,
Sycamore, Hornbeam, Pine, Fir, and Elm ; while
the Lime, as we have seen, has also a leaf attached
to the fruits which answers the same purposes.
Seeds of this character therefore occur on a large
proportion of our forest trees, and on them alone.
But more than this : I have taken one or two
of the most accessible works in which seeds are
figured. I find 30 genera, belonging to 21 dif-
ferent natural orders, figured as having seeds or
fruits of this form. They are all trees or climbing
shrubs, nbt one being a low herb.
4. Let us take another case, that of the plants in
which the dispersion of the seeds is effected by
means of hooks. Now, if the presence of thete
hooks were, so to say, accidental and the dispersion
merely a result, we should naturally expect to find
some species with hooks in all classes of plants.
Fruits and Seeds.
203
They would occur, for instance, among trees and
on water-plants. On the other hand, if they are
developed that they might adhere to the skin of
quadrupeds, then, having reference to the habits
and size of our British quadrupeds, it would be no
advantage for a tree or for a water-plant to bear
hooked seeds. Now, what are the facts ? There
are about thirty English species in which the dis-
persion of the seeds is effected by means of hooks,
but not one of these is aquatic, nor is one of them
more than four feet high. Nay, I might carry the
argument further. We have a number of minute
plants which lie below the level at which seeds
would be likely to be entangled in fur. Now, none
of these, again, have hooked seeds or fruits. It
would seem that, in the histoiy of the earth also,
the appearance of the families of plants in which
the fruits or seeds are provided with hooks coin-
cided with that of the land quadrupeds.
5. Again, let us look at it from another point of
view. Let us take our common forest trees, shrubs,
and tall climbing plants ; not, of course, a natural
or botanical group, for they belong to a number
of different families, but a group characterised by
attaining to a height of, say, over 8 feet. We will
in some cases only count genera ; that is to say,
we will count all the willows, for instance, as one.
These trees and shrubs are plants with which you
are all familiar, and in this country are about 33 in
number. Now, of these 33 no less than 18 have
204
Ffuits and Seeds.
edible fruits or seeds, such as the Plum, Apple,
Arbutus, Holly, Hazel, Beech, and Rose; three have
seeds which are provided with feathery hairs ; and
all the rest, namely, the Lime, Maple, Ash, Syca-
more, Elm, Hop, Birch, Hornbeam, Pine, and Fir,
are provided with wings. Moreover, as will be
seen by the following table, the lower trees and
shrubs, such as the Cornel, Guelder Rose, Rose,
Thorn, Privet, Elder, Yew, and Holly, have gene-
rally edible berries, much eaten by birds. The
winged seeds or fruits characterise the great forest
trees.
TREES, SHRUBS, AND CLIMBING SHRUBS NATIVE
OR NATURALISED IN BRITAIN.
Seed or Fruit.
Edible.
Hairy.
Winged.
Hooked.
Clematis vitalba ....
X
Berberis vulgaris ....
X
Lime ( Tilia Europcea) . .
X
X
Spindle Tree (Euony»itis) .
X
Buckthorn [Rhamnus) . .
X
Sloe {Primus) . . . . ■
X
X
«5
X
o
Hawthorn [Cratxgus) . .
X
Medlar (Mespilus) . . .
X
X
Cornel ( Cornns) . . . .
X
YXdiex {Safnbucus) . . . .
X
Guelder Rose ( Vibuj-nuiii) .
X
Honeysuckle (Lonicera). .
X
Arbutus [Arbutus) . . .
X
Fndts and Seeds. 205
Seed or Fruit.
£,ciiDie.
xi-ciiry.
WTi ncTPfl
Hooked,
X
K^\\\Fraxinus) . . . •
X
Privet [Ltgiislriun) .
X
T.'i 1 r 71 ..... f\
Hop (Huiniilus) . . . .
A U / 1 It... r'\
Hornbeam [Carpiniis) .
X
0
"NT..!- / /"'^i-'jj /•» i-\
X
"A
T» / rr* ,-\
X
_ 1 - / /~\ . . . »\
X
Willow [Salix) . . . .
X
Pnnlnr ( PotillusS . . . .
X
X
X
X
6. Or let us take one natural order. That of the
Roses is particularly interesting. In the genus
Geum the fruit is provided with hooks ; in Dryas it
terminates in a long feathered awn, like that of
Clematis. On the other hand, several genera have
edible fruits ; but it is curious that the part of a
plant which becomes fleshy, and thus tempting to
animals, differs considerably in the different genera.
In the Blackberry, for instance, and in the Rasp-
berry, the carpels constitute the edible portion.
When we eat a Raspberry we strip them off, and
leave the receptacle (the white fleshy part) behind ;
while in the Strawberry the receptacle constitutes
the edible portion — the carpels are small, hard, and
closely surround the seeds. In these genera the
206
Fruits and Seeds.
sepals are situated below the fruit. In the Rose, or
the contrary, the peduncle is swollen and inverted,
so as to form a hollow cup, in the interior of which
the carpels are situated. Here you will remember
that the sepals are situated above, not below, the
fruit. Again, in the Pear and Apple it is the
ovary which constitutes the edible part of the fruit,
and in which the pips are imbedded. At first sight
the fruit of the Mulberry — which, however, belongs
to a different family — closely resembles that of the
Blackberry. In the Mulberry, however, it is the
sepals which become fleshy and sweet.
7. The next point is that seeds should be in a
spot suitable for their growth. In most cases the
seed lies on the ground, into which it then pushes its
little root. In plants, however, which live on trees
the case is not so simple, and we meet with some
curious contrivances. Thus, the Mistletoe, as we
all know, is parasitic on trees. The fruits are eaten
by birds, and the droppings often therefore fall on
the boughs ; but if the seed was like that of most
other plants it would soon fall to the ground, and
consequently perish. Almost alone among English
.plants, it is extremely sticky, and thus adheres to
the bark.
8. Another very interesting genus, again, of the
same family is Myzodendron (fig. 80), a Fuegian
species allied to the Mistletoe, and parasitic on the
Beech. Here the seed is not sticky, but is provided
with four flattened flexible appendages. These
Fruits and Seeds. 207
catch the wind, and thus carry the seed from one
tree to another. As soon, however, as they touch
Fig. 80. — Seed of Myzodendron.
any Httle bough the arms twist round it and there
anchor the seed.
9. In many plants which hve as parasites on trees
the seeds are extremely numerous and minute.
208
Fniiis and Seeds.
Their great numbers increase the chance that the
wind may waft some of them to the trees on which
they grow ; and as they are then fully supplied
with nourishment they do not require to carry any
store with them. Moreover their minute size is an
advantage, as they are carried into any little chink
or cranny in the bark ; while a larger or heavier
seed, even if borne against a suitable tree, would
be more likely to drop off.
Fruits and Seeds.
209
Fig. 81. — A Brazilian Cardamine.
a a, ordinary pods ; b, subterranean pods.
VI.
I. Even among terrestrial species there are many
cases in which plants are not contented simply
P
2 lO
Friiits and Seeds.
to leave their seeds on the surface of the soil, but
actually sow them in the ground.
Thus in the Subterranean Clover, one of our
rarer kinds, only a few of the florets become per-
fect flowers, the others form a rigid pointed head
which at first is turned upwards, and as their ends
are close together, constitute a sort of spike. At
first, I say, the flower-heads point upwards like
those of other clovers, but as soon as the florets
are fertilised, the flower-stalks bend over and grow
downwards, forcing the flower-head into the ground,
an operation much facilitated by the peculiar con-
struction and arrangement of the imperfect florets.
The florets are, as Darwin has shown, no mere
passive instruments. So soon as the flower-head is
in the ground they begin, commencing from the
outside, to bend themselves towards the peduncle,
the result of which of course is to drag the flower-
head further and further into the ground. In most
clovers each floret produces a little pod. This
would in the present species be useless ; many
young plants growing in one place would jostle
and starve one another. Hence we see another
obvious advantage in the fact that only a few
florets perfect their seeds.
2. I have already alluded to our Cardamines,
the pods of which open elastically and throw their
seeds some distance. A Brazilian species (fig. 8l ),
besides the usual long pods (fig. 8i, « a), produces
Fruits and Seeds.
211
also short pointed ones (fig. Si,b b), which it buries
in the ground.
In the case of the Ground-nut of the West
Indies the flower is yellow and resembles that of a
pea, but has an elongated calyx, at the base of which,
and close to the stem, is the ovary. After the flower
has faded, the young pod, which is oval, pointed,
and very minute, is carried forward by the growth
of the stalk, which becomes two or three inches long
and curves downwards so as generally to force the
pod into the ground. If it fails in this, the pod
does not develop, but soon perishes ; on the other
hand, as soon as it is underground the pod begins
to grow and develops two large seeds.
3. In a South European species of Vetch (fig. 82)
there are two kinds of pods. One of the ordinaiy
form and habit {d), the other {b), oval, pale, con-
taining only two seeds borne on underground stems,
and produced by flowers which have no corolla.
Again, a species of the allied genus Lathyrus
(fig. 83) affords us another case of the same pheno-
menon.
There are many other species possessing the
same faculty of burying their seeds, belonging
moreover to very diff"erent families of plants.
4. Moreover, it is interesting that in several of
these the subterranean pods diff"er from the usual and
aerial form in being shorter and containing fewer
seeds. The reason of this is, I think, obvious. In
the ordinary pods the number of seeds of course
212
Fruits and Seeds.
increases the chance that some will find a suitable
place. On the other hand, the subterranean ones
Fig. 82. — Vetch {Vicia amphicarpd).
a a, ordinary pods ; b b, subterranean pods.
are carefully sown, as it were, by the plant itself.
Several seeds together would only interfere with
Fruits and Seeds. 2 1 3
one another, and it is therefore better that one or
two only should be produced.
Fig. 83. — Pea (Lathyrus amphicarpos).
a, ordinary pods ; b, subterranean pods.
5. In the Crane's Bills the fruit is a capsule which
opens elastically, in some species throwing the
214
Fruits and Seeds.
seeds to some little distance. The seeds them-
selves are more or less spindle-shaped, hairy, and
produced into a twisted hairy awn, as shown in fig.
84. The number of spiral turns in the awn depends
upon the amount of moisture ; and the seed may
Fig. 84.— Seed of Crane's Bill.
thus be made into a veiy delicate hygrometer, for
if it be fixed in an upright position, the awn twists
or untwists according to the degree of moisture,
and its extremity thus may be so arranged as to
move up and down like a needle on a register. It
is also affected by heat. Now, if the awn were
Fruits and Seeds. - ^ 5
fixed it is obvious that during the process of
untwisting the seed itself would be pressed down-
wards, and this mechanism thus serves actually
to bury the seed.
6 If a seed of this plant is laid on the ground,
it remains quiet as long as it is dry ; but as soon
as it is moistened— as soon as the earth be-
comes in a condition to permit growth— the outer
side of the awn contracts, and the hairs surround-
ing the seed commence to move outwards, the
result of which is gradually to raise the seed into
an upright position with its point on the soil. The
awn then commences to unroll, and consequently
to lengthen itself upwards, and it is obvious that as
it is covered with reversed hairs, it will probably
press against some blade of grass or other obstacle,
which will prevent its moving up, and will there-
fore tend to drive the seed into the ground. If
then the air becomes diyer, the awn will again
roll up, when from the position of the hairs the
feathery awn can easily slip downwards, and will
therefore not affect the seed. When moistened
once more, it will again force the seed further
downwards, and so on until the proper depth is
obtained. One of the Mountain Anemones again
has essentially the same arrangement, though
belonging to a widely separated order.
7. A still more remarkable instance is afforded by
a beautiful South European grass, Stipa pennata
(fig. 85). The actual seed is small, with a sharp
Fig. 85. — Seed of Stipa, a South European Grass. (Natural size.)
Fruits and Seeds.
217
point, and stiff, short hairs pointing backwards.
The posterior end of the seed is produced into a
fine twisted corkscrew-like rod, which is followed
by a plain cylindrical portion, attached at an angle
to the corkscrew, and ending in a long and beautiful
feather, the whole being more than a foot in length.
The long feather, no doubt, facilitates the disper-
sion of the seeds by wind ; eventually, however, the
seeds sink to the ground, which they tend to reach
(the feather being the lighter portion), point down-
wards. Frank Darwin considers that the seed re-
mains in that position as long as it is dry, but if
a shower comes on, or when the dew falls, the spiral
unwinds, and if, as is most probable, the surround-
ing herbage or any other obstacle prevents the
feathers from rising, the seed itself is forced down
and so driven by degrees into the earth. I have
suggested, on the contrary, that the wind acting on
the feather gradually drives the seeds into the
ground.
2l8
Fruits and Seeds.
VII.
I. I have already mentioned several cases in which
plants produce two kinds of seeds, or at least of
pods, the one being adapted to burying itself in
the ground. There is, in addition, a North African
species of Corydalis which produces two kinds of
seeds (fig. 86), one somewhat flattened, short and
broad, with rounded angles ; the other elongated,
and hooked. In this case the hook in the latter
form perhaps serves for dispersion.
2. Our common Lesser Hawkbit (fig. 76, b) also
possesses, besides the fruits with the well-known
feathery crown, others which are destitute of such
6
Fig. 86. — Seeds of Corydalis.
Fruiis and Seeds. i 219
a provision, and which probably therefore are
intended to take root at home.
Mr Drummond has described a species of Alis-
macav which has two sorts of seed-vessels ; the one
produced from large floating flowers, the other at
the end of short submerged stalks. He does not,
however, describe either the seeds or seed-vessels
in detail.
3. Before concluding I will say a few words as to
the very curious forms presented by certain seeds
and fruits. The pods of Lotus, for instance, quaintly
resemble a bird's foot, even to the toes ; whence the
specific name of one species, ornithopodioides, which
means " like a bird's foot" ; those of Hippocrepis re-
mind one of a horseshoe ; those of Trapa bicornis
have an absurd resemblance to the skeleton of a
bull's head. These likenesses appear to be acci-
dental, but there are some which probably are of use
to the plant. For instance, there are two species of
Scorpmrus (fig. 87) , the pods of which lie on the
ground, and so curiously resemble, the one (fig. 87, rt)
a centipede, the other (fig. 87, b) a worm or cater-
pillar, that it is almost impossible not to suppose
that the likeness must be of some use to the plant.
The pod of a kind of Biserrula (fig. 88) also
has a striking resemblance to a flattened centipede ;
while the seeds of Abrics, both in size and in their
very striking colour, mimic a small beetle, Artemis
circiiviusta.
4. Mr. Moore has recently called attention to other
220
Fruits and Seeds.
Fruits and Seeds.
cases of this kind. Thus the seed of Martynia
diandra much resembles a beetle with long an-
tenna ; several species of Lupins have seeds much
like spiders, and those of a gourdlike plant,* mimic
a piece of dry twig. In the common castor oil
plants (fig. 89), though the resemblance is not so
Fig. 88.— Pod of BiSERRULA.
Fig. 89.— Seed of Castor Oil Plant.
close, still at a first glance the seeds might readily
be taken for beetles or ticks. In many plants allied
to Euphorbia plants, as, for instance, in Jatropha
(fig. 90), the resemblance is even more striking.
The seeds have a central line resembling the space
between the elytra, or wing cases, dividing and
* Dimorphochlamys,
222
Fridts and Seeds.
slightly diverging at the end, while between them
the end of the abdomen seems to peep ; at the
anterior end the seeds possess a small lobe, which
mimics the head or thorax of the insect, and which
even seems specially arranged for this purpose ; at
least it would seem from experiments made at Kew
that the removal of this little lobe does not injure
the seed.
5. These resemblances might benefit the plant in
one of two ways. If it be an advantage to the
plant that the seeds should be swallowed by birds,
''1
\
V
i
ii
Fig. 90. — Seed of Jatropha.
their resemblance to insects might lead to this
result. On the other hand, if it be desirable to
escape from grain-eating birds, then the resem-
blance to insects would serve as a protection. We
do not, however, yet know enough about the habits
of these plants to solve this question.
6. Indeed, as we have gone on, many other ques-
tions will, I doubt not, have occurred to you, which
we are not yet in a position to answer. Seeds, for
instance, differ almost infinitely in the sculpturing
Fruits and Seeds. 223
of their surface. I shall have failed woefully in
my object if I leave you with the impression that
we know all about seeds. On the contrary, there
is not a fruit or a seed, even of one of our com-
monest plants, which would not amply justify and
richly reward the most careful study.
7. In this, as in other branches of science, we have
but made a beginning. We have learnt just enough
to perceive how little we know. Our great masters
in natural history have immortalised themselves by
their discoveries, but they have not exhausted the
field ; and if seeds and fruits cannot vie with
flowers in the brilliance and colour with which they
decorate our gardens and our fields, still they surely
rival them in the almost infinite variety of the
problems which they present to us, the ingenuity,
the interest, and the charm of the beautiful con-
trivances which they offer for our study and our
admiration.
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