Do ants sow and reap?—Rival observers—The Texan _v._
Macaulay’s schoolboy—More evidence wanted—How ants cross
rivers—Tubular bridges—Ant armies—A world in flight—Living
nests—Ants and plants—Mutual dependence—Nests in thorns and
tubers—Ant honey-pots—Business humanity—Burial customs—A
strange observation—Two views of ants.
MUSHROOM-GROWING, especially if the ants plant the mushrooms in the way
stated by Mr. Tanner, is just as extraordinary, I think, as their habit
of planting a field with ant-rice and reaping it at the proper time
would be, did they really practise it. Up to a little while ago it
certainly seemed as though they did, for there was Dr. Lincecum’s
definite statement based upon twelve years’ observation, and this, if
not confirmed by Mr. McCook, was, at any rate, not contradicted by him.
On the contrary, McCook mentioned a good many facts pointing in the
direction of Lincecum’s assertion, and though he did not consider them
decisive, he could see no reason why the ants should not act in this
way, as indeed there is none: so that as he had only stayed a few months
where Lincecum had lived for twelve years, he seemed like a weaker
witness supporting, according to his opportunities of observation, a
much stronger one. Now, however, comes another witness, whose
opportunities have also been great, and in a somewhat heavy-handed way,
in a spirit of myth-slaying and irrelevant reference to supposed
schoolboy knowledge, hardly required in face of all that ants are known
to do, denies the whole thing.
First, however, let us have the assertion as originally made by
Lincecum, which is, that on the summit of the mound of their nests, from
which they carefully clear away all other vegetation, the harvesting
ants sow the seed of a certain plant called ant-rice for the purpose of
subsequently reaping a harvest of the grain. It is sown in time for the
autumnal rains to bring up, and at the beginning of November a green row
or ring of ant-rice, about four inches wide, is seen springing up round
the circumference of the _disk_ (as the circular top of the mound is,
for some reason, always called). In the vicinity of this circular ring
the ants do not permit a single spire of any other grass or weed to
remain a day, but leave the aristida or ant-rice untouched until it
ripens, which occurs in June of the next year. After the maturing and
harvesting of the seed, the dry stubble is cut away and removed from the
disk, which is thus left unencumbered until the ensuing autumn, when the
same species of grass again appears as before, and so on.[74] After
stating in a letter to Darwin that he has seen all this taking place
year after year, Dr. Lincecum adds:—“There can be no doubt of the fact
that the particular species of grain-bearing grass mentioned above is
intentionally planted. In farmer-like manner the ground upon which it
stands is carefully divested of all other grasses and weeds during the
time it is growing. When it is ripe the grain is taken care of, the dry
stubble cut away and carried off, the paved area being left unencumbered
until the ensuing autumn, when the same ant-rice reappears within the
same circle and receives the same agricultural attention as was bestowed
upon the previous crop, and so on year after year, as I _know_ to be the
case in all situations where the ants’ settlements are protected from
graminivorous animals.”[75] Lincecum also believed that the ants were
able in some way to prevent the seed stored in their nests from
germinating. This same fact has been asserted, and apparently proved, by
Moggridge, in regard to the harvesting ant of southern Europe, and he
also states that, if in spite of the precaution any seeds begin to
sprout, the ants by gnawing off the tips of the radicles would prevent
the germination from proceeding.
This, then, is the case _for_ the harvesting ant, as we may say; for if
these things be true they are certainly much to its credit, whereas, if
not, the scandal is so great that it ought to change its name. Let us
now hear the case against, as stated by Professor Wheeler, after which
readers may make up their minds, if they can, for I have not quite done
so yet. I quote in full, so that the two statements may be balanced
against each other, and this, I hope, will be more interesting than the
usual “Mr. So and So, however, disputes this and thinks, etc.”—another
line or two in which the contrary proposition of the one before is
stated at about the same length. This is what Professor Wheeler, who
“speaks home—you may relish him more (or at least as much) in the
soldier as the scholar”—has to say: “It may not be altogether out of
place in this paper to record a few other observations on _Pogonomyrmex
molifacieus_, inasmuch as this form has been singled out among all the
known members of the genus as presenting certain remarkable instincts.
Lincecum is responsible for the myth that this _Pogonomyrmex_ sows a
certain species of grass, the ‘ant-rice’ (_Aristida oligantha_),
protects it from harm and frees it from weeds while it is growing, for
the purpose of reaping the grain. This notion, which even the Texan
schoolboy (not Macaulay’s, who probably knew as much about it) has come
to regard as a joke, has been widely cited, largely because the great
Darwin stood sponsor for its publication in the Journal of the Linnean
Society. McCook, after spending a few weeks in Texas observing the ant
in question and recording his observations in a book of 310 pages,
failed to obtain any evidence either for or against the Lincecum myth
and merely succeeded in extending its vogue by admitting its
plausibility. Two years of nearly continuous observation enable me to
suggest the probable source of Lincecum’s and McCook’s misconceptions.
In either case the observer has started with a few facts, and has then
stopped short to draw inferences before gathering more facts. If the
nests of _Molifacieus_ be studied during the cool winter months—and this
is the only time to study them leisurely and comfortably, since the cold
subdues the fiery stings of their inhabitants—the seeds which the ants
have garnered in many of their chambers will often be found to have
sprouted. It is, therefore, certain that these ants are not able to
prevent the seed from germinating, as Moggridge claims for the European
species of Messar, except by conveying them to drier chambers; and in
protracted spells of wet weather even this precaution seems to be of no
avail. On sunny days the ants may often be seen removing these seeds
when they have sprouted too far to be left for food, and carrying them
to the refuse heap, which is always at the extremity of the cleared
earthern disk or mound. In this place the seeds thus cast away as
inedible often take root, and, somewhat later, form an arc of tall grass
more or less closely approximating to a complete circle round the nest.
Since these ants feed largely, though by no means exclusively, on
grass-seeds, and since these particular seeds are a very common and
favourite article of food, it is easy to see how their grass should
often predominate in the circle. In reality, however, only a small
percentage of the nests, and only those situated in certain localities,
present such circles. Now to state that the ant, like a provident
farmer, sows this cereal, and guards and weeds it for the sake of
garnering its grain, is as absurd as to say that the family cook is
planting and maintaining an orchard when some of the peach-stones which
she has carelessly thrown into the backyard, with the other kitchen
refuse, chance to grow into peach trees.”[75] Certainly such a thing
should have been observed before the statement was made, and, if it has
not been, the facts seem more probably accounted for on the above
explanation.
Professor Wheeler goes on to say that “there are several other facts
which show that the special ring of grass about the nest is an
unintentional and inconstant result of the activities of the ant colony.
For instance, one often finds very flourishing ant-colonies that have
existed for years in the midst of much-travelled roads, or in stone
side-walls, often a hundred or more feet from any vegetation whatever
(without any ant-rice on their mounds therefore). Again, it is very
evident that even a complete circle of grass like those described by
Lincecum and McCook would be entirely inadequate to supply more than a
very small fraction of the grain necessary for the support of a
flourishing colony of these ants. Hence they are always obliged to make
long trips into the surrounding vegetation, and thereby wear out regular
paths, which radiate in different directions, often to a distance of
forty to sixty feet from the entrance of the nest. The existence of
these paths, which are often found in connection with grass-encircled
nests, is alone sufficient to disprove Lincecum’s statements.”[75] It
certainly seems easier to suppose that Lincecum misinterpreted certain
facts, not themselves in dispute, than that an explanation on which so
many considerations seem to throw doubt is the correct one. One thing,
at least, seems certain—if some of these ant communities grow grain of
set purpose, all of them do not. This may be possible, but more proof of
it than Lincecum has brought is demanded. If the ants really sow and
reap the grain that grows upon their mounds, and, more especially, if
they carefully keep the patch clear, it ought not to be difficult to see
them doing so. This last would be decisive, whereas the other two are by
no means so.
That ants should use their own larvæ like a shuttle, and for the same
purpose, seems as strange a thing as one can well imagine, but there is
no doubt at all about it, the act having been witnessed on various
occasions by competent observers, whose evidence is mutually
corroborated. The species in question is common in Eastern Asia, and is
accustomed to make little houses or arbours for itself by bending leaves
round so that the edges meet, and then fixing them together, as some
caterpillars do. Now the larva can do something which the grown ant
cannot, which is to spin a cocoon from a sort of gummy, thread-like
substance which issues from the mouth. Whilst one group of ants
therefore join to keep the leaf bent in the proper position, another
take each a larva in their jaws, and pass it from edge to edge of the
leaf, applying its mouth to each edge, until the two are bound firmly
together.[76] Whether this is a more or less remarkable habit than
growing mushrooms it would be difficult, perhaps, to decide, nor is
there any need to try, since such questions are more interesting left
uncertain.
It is well known, or at least credibly asserted, that ants cross rivers
by clinging one to another from the branch of a tree overhanging the
water, till the end of this living chain, as it becomes longer and
longer, is carried by the force of the current to the opposite bank,
where a bridge is formed, over which the main body marches.[77]
According to Du Chaillu the ants in Africa make, not only a bridge, but
a tunnel—“a high, safe tubular bridge through which the whole vast
regiment marches in regular order.”[78] These are the celebrated driver
or bashikouay ants, who, when upon their terrible marauding marches, put
every living creature, including man, to flight, though for many flight
is in vain. Size and strength are here no protection. “The elephant and
gorilla fly before them; the black men run for their lives.” So says Du
Chaillu, and, sure enough, when the skins of some of the poor gorillas
he shot arrived in England, several of these ants were found amongst the
hair.[79] In the forests of equatorial Africa, abounding—if they have
not all been shot by this time—with large animals, these hunting-raids
must give rise to some stirring scenes. What crashings through the trees
and undergrowth! What uncouth sounds, perhaps, of mingled pain and rage!
How a bitten gorilla would express himself! What a subject for a picture
if a herd of elephants, a few families of gorillas, a score or so of
lions, with a few leopards, and baboons, perhaps a rhinoceros, and any
number of antelopes, were all to come rushing down together to where an
artist stood ready for them! I should like to see the picture he would
draw.
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[Illustration: PURSUED BY DRIVER ANTS]
[Illustration]
The greatest beasts of the forest will fly before these terrible little
insects,
one of which is shown in the left-hand corner.
A more remarkable sight even than an ant-bridge is perhaps an ant-nest,
by which I mean, not an ants’ nest in the ordinary sense of the term,
but a nest made of ants. The following quotation from the
much-containing _Naturalist in Nicaragua_, page 25, will explain this
hard saying. “They make their temporary habitations in hollow trees, and
sometimes underneath large fallen trunks that offer suitable hollows. A
nest that I came across in the latter situation was open at one side.
The ants were clustered together in a dense mass like a great swarm of
bees hanging from the roof, but reaching to the ground below. Their
innumerable long legs looked like brown threads binding together the
mass, which must have been at least a cubic yard in bulk, and contained
hundreds of thousands of individuals, although many columns were
outside, some bringing in the pupæ of ants, others the legs and
dissected bodies of various insects. I was surprised to see in this
living nest tubular passages leading down to the centre of the mass,
kept open just as if it had been formed of inorganic materials. Down
these holes the ants who were bringing in booty passed with their prey.”
Of the many curiously constructed or strangely produced dwellings of
ants, this made out of their own bodies is amongst the most remarkable.
Many ants live in the interior of various plants. The plant generally
benefits as much as the insect by this arrangement, so that there is a
mutual dependence between the two, which in some cases is carried to
such an extent that the life of one or both seems a necessary part of
that of the other. In Borneo, for instance, a certain large tuber which
grows on the branches of aged trees is always found inhabited by a
certain red ant, of small size, but fierce disposition, which rushes out
and attacks anyone who ventures at all near its dwelling. The seed of
this tuber is disseminated in the same way as is our own mistletoe,
through the agency of birds, that is to say, the seed being surrounded
by a similar pulpy mass, which adheres to the branch on which it falls.
Soon after germination the tuber, which is shaped something like a
carrot, begins to develop, but whilst still quite small its growth
ceases and in this state it would remain, and before long, die, if it
should not happen to be found by the ants in question. If it should be,
however, its life is assured. They immediately bore a hole at the base
of the stem, upon which this enlarges to a great degree, so that soon
there is room for them to excavate galleries in the cellular tissue of
the interior, and to form a populous colony. The whole tuber is soon
perforated in all directions, and becomes a living and growing
formicarium, the great accretion of cellular tissue which has made this
possible having been caused by the poison—if we may call it so—of the
ant’s bite, in the same way as the sting of the gall-fly raises galls
upon the oak.[80] Of course, from the moment that the ants appear the
tuber is safe from any other insect, or small bird, or mammal that might
otherwise do it harm. The ants in defending their nest would defend it,
and it is on this principle of mutual advantage that such ant and plant
alliances have been brought about.
Thus the dry, arid plains, called savannahs, of tropical America support
a species of acacia of which the thorns, characteristic of the family,
grow in pairs and are shaped exactly like the horns of some oxen. Every
pair of these horns becomes in time an ants’ nest, and if the tree be
touched or shaken, the ants rush out full of fury in defence of their
habitations. Thus every tree is tenanted by a large army of retainers,
who almost more than the thorns themselves, which have been developed
for the same purpose, protect it against browsing quadrupeds. Its
thorns, however, would be no protection against the leaf-cutting ants in
search of materials for their mushroom-beds, whereas these are kept at
bay by a hostile species, smaller indeed, but armed with a powerful
sting. “For these services,” says Belt, “the ants are not only securely
housed by the plant, but are provided with a bountiful supply of food;
and to secure their attendance at the right time and place, this food is
so arranged and distributed as to effect that object with wonderful
perfection. The leaves are bi-pinnate (double, that is to say), and at
the base of each pair of leaflets, on the mid-rib, is a crater-formed
gland, which, when the leaves are young, secretes a honey-like liquid.
Of this the ants are very fond; and they are constantly running about
from one gland to another to sip up the honey as it is secreted. But
this is not all; there is a still more wonderful provision of solid
food. At the end of each of the small divisions of the compound leaflet
there is, when the leaf first unfolds, a little yellow, fruit-like body,
united to it by a point at its base. Examined through a microscope, this
little appendage looks like a golden pear. When the leaf first unfolds
the little pears are not quite ripe, and the ants are continually
employed going from one to another examining them. When an ant finds one
sufficiently advanced it bites the small point of attachment; then,
bending down the fruit-like body, it breaks it off and bears it away in
triumph to the nest. All the fruit-like bodies do not ripen at once, but
successively, so that the ants are kept about the young leaf for some
time after it unfolds. Thus the young leaves are always guarded by the
ants; and no caterpillar or larger animal could attempt to injure them
without being attacked by the little warriors.” Thus, as Mr. Belt very
aptly puts it, “the ants are really kept by the acacia as a standing
army to protect its leaves from the attacks of herbivorous mammals and
insects.”[81]
As for the honey or honey-pot ants, they were first heard of in America,
and various floating stories, which seemed more or less hard to credit,
having got into circulation about them, without there being any positive
knowledge to check them, Dr. McCook, to remove this grave reproach to
transatlantic entomology, started off one day to observe them. He soon
found that the main fact which had been stated was correct, viz. that a
certain sect or caste of these ants, disregarding the Italian warning,
were in the habit of making themselves all honey, to be swallowed in
consequence by the rest of the community. These are the so-called
honey-pots, and so well do they deserve their name, that when full the
abdomen becomes almost perfectly circular, like a glass globe, and so
enormously swollen that the body in proportion to it is like a grain of
wheat stuck into a cherry or gooseberry.[82] The legs dangle towards the
ground, but hardly, or only by a great effort, reach it, and in this
last state of distension the insect may find it impossible to get about,
though as a rule by dragging or pushing herself along sideways, she is
able to do so to a certain extent. These honey-jars have special
chambers for their accommodation, and here they hang in clusters from
the roof, awaiting the visit of any worker, who upon signifying his
wants—it would seem after climbing up to them—is fed, after the ordinary
ant manner, by regurgitation. In the same way the honey-bearers are
themselves filled, or more properly speaking, feed themselves, since the
mouth arrangement, in spite of the direction in which things seem
hastening, has not yet become so simple as in the case of a real jar.
The honey which the rotunds, as McCook calls them, receive from the
workers is gathered at night, and is obtained almost entirely from the
galls of oak trees, which, when pierced by the ant’s mandibles, exude a
white transparent liquid in minute globules. This is greedily licked up
by the ants and distributed by them after the return home, not only to
the rotunds, but to such of their fellow-workers as may not have taken
part in the expedition.[83] The honey thus obtained is pleasant to ant
and human taste alike, and the Indians of New Mexico, as no doubt
elsewhere, obtain it by the simple process of squeezing the
insect—breaking the honey-jar, as one may say. They also make from it a
fermented liquor having intoxicating powers, so that one need not wonder
that the idea of farming the honey-ant, like the honey-bee, has been
seriously discussed in the United States. McCook, however, has pointed
out that “the limited quantity of the product would prevent a profitable
industry,” and he adds: “Besides, the sentiment against the use of honey
thus taken from living insects, which is worthy of all respect, would
not be overcome.”[83] Personally I think it would be overcome, and
pretty quickly, too, as are most other sentiments that stand in the way
of pleasure or profit. Women would get it under first, as in the case of
birds, seals, etc., and the world would soon follow, with “woman’s
influence” upon its lips. But let me not be unjust. I do not believe in
sentiment as a working force in the case at all. If the ants are not to
be squeezed it will be on commercial considerations.
That the worker-ants—and for that matter the others also—are extremely
fond of the honey so curiously stored by them, will be easily believed,
and an unpleasant illustration of their greediness in this respect was
often observed by McCook when capturing a nest. The swollen bodies of
the rotunds, on these occasions, were sometimes unavoidably ruptured,
whereupon such workers as happened to be near these unfortunates,
forgetting their alarm, which had hitherto been great, and the ruin and
confusion all around them, paused in their flight, or aimless movements,
and greedily lapped up the overflowing honey.[84] It is all the more
interesting, therefore, to learn that when the “little life” of these
poor honey-pots is at length “rounded with a sleep,” their contained
treasure, though so easily obtainable, goes with them to the grave, the
idea of opening the full crop, and imbibing the contents, never seeming
to occur to any ant. This is all the more remarkable in that the
workers, when they recognise that life is extinct, carefully separate
the abdomen from the thorax by sawing through, with their mandibles, the
little connecting stalk called the petiole. The two parts are then
removed separately, that representing the head half being carried,
whilst the “golden bowl” of the body “unbroken,” though with “the spirit
fled for ever,” is rolled along the various chambers and galleries of
the nest, till it finally finds a resting-place in the cemetery just
beyond its precincts.[84] To what are we to attribute the
non-utilisation of the honey in the dead body? Even were it possible
that the ants could forget that it was there, they cannot be unconscious
of what must be smelt, as well as seen, through the semi-transparent
walls of the abdomen. Some feeling must restrain them—what, I am not
prepared to say in a work which does not aim at being scientific.
Here, then, we have one most suggestive illustration—“suggestive,” I
think, is a very useful word—of the funeral habits of ants. Many others
could be instanced, but I will end this chapter, and small account of
ant doings, generally, with the following extract from the _Proceedings
of the Linnæan Society_ (1861). The observer was a Mrs. Hutton, of
Sydney; and Romanes, who quotes her account in his _Animal
Intelligence_, remarks that though she is not a well-known observer the
facts reported were such as scarcely to admit of a mistake. Personally,
I attach no weight whatever to anybody’s not being known as an observer.
Want of leisure, or unpropitious circumstances generally, must prevent
large numbers of people from seeing what they would be very well able to
note accurately if they did, or from recording what they do see; whilst,
on the other hand, leisure, joined to taste in a certain direction,
makes many a quite average observer known as a good one. A good
observer, in fact, is rather one who is always keeping on, and does not
weary, than one who can see a single salient thing more plainly than
most other people; and, again, it is easy to set a fictitious value
merely on being before the public.
Having thus defended Mrs. Hutton, I proceed now to quote her account: “I
saw,” she says, “a large number of ants surrounding the dead ones”
(soldier ants which she had herself killed and left lying on the ground
some half-hour previously), “and determined to watch their proceedings
closely. I followed four or five that started off from the rest towards
a hillock a short distance off, in which was an ants’ nest. This they
entered, and in about five minutes they reappeared, followed by others.
All fell into rank, walking regularly and slowly, two by two, until they
arrived at the spot where lay the dead bodies of the soldier ants. In a
few minutes two of the ants advanced and took up the dead body of one of
their comrades; then two others, and so on, until all were ready to
march. First walked two ants bearing a body, then two without a burden;
then two others with another dead ant, and so on, until the line was
extended to about forty pairs, and the procession now moved slowly
onwards, followed by an irregular body of about two hundred ants.
Occasionally the two laden ants stopped, and laying down the dead one,
it was taken up by the two walking unburdened behind them, and thus, by
occasionally relieving each other, they arrived at a sandy spot near the
sea. The body of ants now commenced digging with their jaws a number of
holes in the ground, into each of which a dead ant was laid, where they
now laboured on until they had filled up the graves. This did not quite
finish the remarkable circumstances attending this funeral of the ants.
Some six or seven individuals had attempted to run off without
performing their share of the task of digging; these were caught and
brought back, when they were at once attacked by the body of ants and
killed upon the spot. A single grave was quickly dug, and they were all
dropped into it.”
“Prodigious!” as Dominie Sampson would have said, and certainly I think
this is one of the most remarkable observations upon ants that has ever
been made. As far as the burying is concerned, it has been corroborated
by the Rev. W. Farrar White, who, at the same time, corroborates Pliny;
but how strange are all the circumstances! What was it, one wonders,
that made just a few of the crowd shirk their share of the labour—for
this is not like ants. Some strange, uncanny feeling in connection with
the dead bodies may be suspected; but seeing that, as the Russian
proverb truly says, “Another man’s soul is darkness,” it is not very
likely that we shall ever know what ants feel.
One interesting question is suggested in this connection, though I have
never known it raised yet. Two views of what ants are, excluding
compromises, may be taken—the automatic one, tempered with “psychic
plasticity,” of Professor Wheeler, and that formed by Mr. Belt, who,
having fully satisfied himself—from the keenest observation, be it
remembered—of their reasoning powers and capacities, remarks, “When we
see these intelligent insects dwelling together in orderly communities
of many thousands of individuals, their social instincts developed to a
high degree of perfection, making their marches with the regularity of
disciplined troops, showing ingenuity in the crossing of difficult
places, assisting each other in danger, defending their nests at the
risk of their own lives, communicating information rapidly to a great
distance, making a regular division of work, the whole community taking
charge of the rearing of the young, and all imbued with the strongest
sense of industry, each individual labouring not for itself alone, but
for all its fellows, we may imagine that Sir Thomas More’s description
of Utopia might have been applied with greater justice to such a
community than to any human society.”[85] Now, if Belt’s view be the
correct one, or if the evidence in favour of it be at all strong, is it
not time for us to ask ourselves, merely as a moral problem, how far we,
in our clumsy and imperfect human state, have a right to kill ants and
tumble Utopia to pieces, simply for our amusement, intellectual or
otherwise? Ought we to do this? Or ought we, like a lady who lives in
America and writes to very scientific papers, to imprison queens who do
no harm, and make ourselves learned at the expense of one, or both of
their antennæ, during the term of their natural lives? However simply
and sweetly we may talk of this, however much true womanly feeling may
enter into the narrative, nay, even though we give the queens pet names,
is it really right?
-----
Footnote 74:
Romanes, Animal Intelligence, pp. 106-107.
Footnote 75:
The American Naturalist, February, 1902.
Footnote 76:
The Cambridge Natural History, vol. 6.
Footnote 77:
Du Chaillu, Adventures in Equatorial Africa, pp. 312, 313.
Footnote 78:
J. G. Wood, Homes Without Hands, p. 452.
Footnote 79:
W. F. Kirby, Marvels of Ant life, p. 73.
Footnote 80:
Dr. Beccari’s account, quoted in the _Popular Science Review_, 1875.
Footnote 81:
Belt, The Naturalist in Nicaragua, pp. 219, 220.
Footnote 82:
The ideal of what a short-billed tumbler pigeon’s head should be.
Footnote 83:
McCook, The Honey-Ant of the Garden of the Gods.
Footnote 84:
The American Naturalist, February, 1902.
Footnote 85:
Belt, The Naturalist in Nicaragua, pp. 28, 29.
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