The provisions collected by these two birds reveal a remarkable fact. They possess indeed two distinct diets; they do not preserve for the period of famine the overplus of the foods which they consume in the period of abundance. They chase insects and feed on them as long as they can find them, while they gather up in their storehouses an entirely different food.

Physiological reserves. — All the animals of which I have just spoken place their provisions for the future in barns in the same manner as Man. Those who have not this foresight are either able to nourish themselves in all seasons by the chase, or else, after having feasted one half of the year, they fast during the other half. In the latter case they consume during the fasting period a portion of their own substance, and use up materials placed in reserve in their organism, in the form of fat for example. This arrangement, which allows them to prolong life, though growing thin, until the next season of prosperity, is not under the control of the will. It is a complication of physiological phenomena resulting from the functioning of different parts of the organism.

Stages between physiological reserves and provisions. — Between physiological reserves and industrial stores we may place as an intermediate stage the interesting case of the Honey Ants.53

These insects (Myrmecocystus) live in Texas, and form colonies in which certain individuals play a very special part They exaggerate to an extreme point the power of preserving provisions in their crops. These materials are not assimilated; they do not form part of the animal’s body, and although placed inside it cannot be compared to physiological reserves. It is especially curious that they are not to be utilised only by the animal itself, but also by the other members of the colony who are not able to form such stores. Among the Myrmecocystus there are workers of two sorts; the first kind resemble other ants with some differences of detail, and build and hollow the earth nest which shelters the community. The second kind is quite different; the abdomen in these workers is enormously distended so as to constitute a voluminous sphere, which may become four or five times larger than the thorax and head together. (Fig. 12.) On this distended receptacle appear several darker plates; these are the remains of the chitinous parts of the primitive wings. In the fine season these ants go out in a band and collect a sweet liquor which forms pearly drops on certain galls of oak leaves. These drops, elaborated into honey, gradually fill the crop, distending it and pushing back neighbouring organs until it receives its globular form. When they have arrived at this obese condition, the heavy honey ants no longer leave the nest. They remain without movement, hanging by their legs to the roof or lying against the walls of a room. The workers who have remained slender come and go, attending to their usual occupations, and pass near the others without paying attention to them or going out of the way to lend assistance to their impotent sisters when one of them has rolled over on the ground and can no longer arise unaided. (Fig. 13.) They only cease to be indifferent when impelled by the selfish sentiment of hunger, and then it is to ask and not to give assistance. The fat ants in fact could not themselves consume all the honey that they have elaborated; the others in times of famine approach them, caress them with their antennÆ, and obtain by solicitation a drop of honey which the large ones disgorge from the crop. Here, then, is a colony in which the division of labour has reached a remarkable degree of polymorphism. Some of the members accomplish the work of engineers and masons, while the others fabricate for the community a store of honey. Instead of depositing these provisions in cells like bees, they preserve them in their own digestive tube. This custom has re-acted to such an extent on the form of their bodies that at first sight they seem to belong to a different species.

Animals who submit foods to special preparation in order to facilitate transport. — Not content with collecting materials as they are found in nature, certain animals submit them to preparation with various aims, either to render transport easier or that they may not deteriorate when stored. Among those of whom I have just spoken, some collect with the view of utilising their stores in a more remote future than others. The Ateucus sacer intends to consume the provisions he prepares almost immediately. Yet he acts in so careful a manner that I cannot pass him in silence. This beetle is the sacred ScarabÆus so venerated by the Egyptians, who have everywhere reproduced his image in porphyry and granite. He is a most singular insect. The celebrated Fabre has given a complete and very picturesque history of his customs.54 I have myself had an opportunity of seeing him at work. It was in Persia, in the plain of Susiana, on a hot morning in March. We had passed the night in the open air, proposing to continue our journey in the early morning, but our mules, rendered rather lively by the fresh grass brought out by the spring weather, had decided otherwise. They had all decamped to take a ramble on their own account. In order to pass away the hours taken up by the muleteers in searching for the strayed animals, the ScarabÆus would, I thought, furnish me with an amusing and instructive spectacle. During the night the mules had not failed to leave here and there the relics of their digestion. The aroma, borne on the morning breeze, had struck the ScarabÆus on awaking. It was his favourite dish. From all points of the sky their heavy silhouettes could be seen against the blue. It was still fresh, the sun having only risen about an hour before; the heat would soon become oppressive, and the sybaritic beetle, without attending to his morning appetite, which his fresh meal could not fail to excite, nourishes the bourgeois dream of making his little pile in order to enjoy himself sheltered from the hot rays. Immediately on arriving on the scene of the accident each began to display feverish activity. All set to work. With their heads, the anterior edge of which is flat and supplied with six strong spines, they raised their provisions; with their anterior feet, which are large and also armed with spines, they moulded the paste and placed it beneath the abdomen between the four other legs, giving it a rounded form. Little by little the sphere increased and acquired the size of a small apple. That was sufficiently large, and besides it was already becoming hot. The insect set about carting away his prize to a sheltered dining-room. He placed his four posterior legs on the ball; with the two last, which were continually moving, he made certain of the equilibrium of the mass; then resting his head and two anterior feet on the ground he pushed backwards, and with extreme rapidity. (Fig. 14.) There was enough for all; each worker could find the just reward for his labour; I witnessed none of the regrettable facts narrated by Fabre. It happens sometimes, according to this ingenious observer, that a cunning ScarabÆus, who has taken no part in the laborious labour of moulding the paste, arrives when it is on the road to aid the convoy, or even simply to pretend to help, in order that when the moment has come he may claim a share in the coveted meal, or even carry it all away if he can profit by a momentary inattention on the part of the lawful proprietor. I followed one of these Coleoptera for more than five metres from the place where his labour began. After having deposited his ball he began to dig up the earth around it;55 but the mules had returned and I was obliged to depart.

I have no doubt that subsequent events were not exactly the same as narrated by Fabre for the ScarabÆus of Provence. The insect having made his hole, buries himself in it for a tÊte À tÊte with the precious sphere. He immediately sets about passing the whole through his body. Without haste but without rest, for a week or a fortnight, as long as there is any of it left, he eats continuously, and continuously digests. He does not stop for a moment, his jaws are working the whole time; and Fabre has called attention to the fact that from the opposite extremity of the animal a continuous thread emerges without breaking, and becomes coiled up.

Care bestowed on harvested provisions. — Among the animals who take particular care of the provisions they have amassed, special mention must be made of certain species of Ants. It was formerly believed that these industrious Hymenoptera are not accustomed to store up in barns for the winter. This opinion long prevailed owing to the authority of Huber, so competent in these matters, although the ancients were well acquainted with the storehouses of ants.56 But it was founded on an exclusive study of these insects in northern countries, in which, during the cold season, they become torpid and buried in their hybernal sleep. Naturally they have no need of food during this period, but it was incorrect to generalise from this fact. The ants of the south are active all the year round. An English naturalist, Moggridge, who passed several winters at Mentone, has placed this fact out of doubt. Suffering from an incurable disease, he occupied the last years of his life in observing and setting down for the instruction of others the habits of these insects. He found that ants of the species Atta barbara store up grains. They utilise plants of various kinds, but usually fumitory, oats, nettle, various species of Veronica, etc. They procure these grains towards the end of autumn, collecting them on the soil, or even, when they do not fall in sufficient quantities, climbing up the plants and gathering them in position. An ant will, for instance, ascend the stem of a fruiting plant, of shepherd’s-purse, let us say, and select a well-filled but green pod, mid-way up the stem, those below being ready to shed their seeds at a touch. Then seizing it in its jaws, and fixing its hind legs firmly as a pivot, it contrives to turn round and round, and so to strain the fibres of the fruit-stalk until they snap; it then patiently backs down the stem. Sometimes two ants combine their efforts; one, at the base of the peduncle, gnaws at the point of greatest tension, while the other hauls upon it and twists it. And sometimes the ants drop the capsules to their companions below, corresponding with the curious account given by Ælian of the way the spikelets of corn are thrown down “to the people below.” In this labour they display the activity usual in their race, and do not stop until they have carried away to their barns the amount of provision they desire. When their wealth is stored up in the nest, the ants pile up the grains in some hundred little rooms designed for this purpose, each measuring from seven to eight centimetres in diameter, and three or four in height; the average granary being about the size of a gentleman’s gold watch. Adding up the quantities of grain divided between these different barns, it is found that they may be estimated at about 500 or 600 grammes, which represents a very large number of meals for such small appetites, and must cost colossal labour if we take into consideration the size of the workers. But when the harvest is completed, the Atta barbara have not completed their task; they are too ingenious to limit themselves to waiting with crossed legs for the moment to come when they may enjoy their labour, without considering the damage that may arise. Their first care is to prevent the grains from germinating for some weeks. How they obtain this result is not exactly known, but it is certain that germination does not take place, although all the conditions of heat and moisture offered by the interior of the ant-hill are favourable to it; it is not less certain that this arrest is due to the ants. This is shown in a very simple manner. It is sufficient to prevent the access of the insects to one of these chambers to cause the grains to germinate immediately. We can only suppose some direct action of the ants, every other hypothesis falling before this single fact: the arrested phenomenon is produced as soon as the Atta barbara no longer acts on it. Therefore they arrest germination without rendering it impossible, and when the moment arrives for utilising the accumulated stores, their first care is to allow the grains to follow the normal course of evolution. The envelope breaks, the little plant makes its appearance; radicle and stalk come to light. But the ants do not permit the development to go too far. The little plant, in order to grow, digests the starch which is associated with the albumen, for it is not yet able to draw its nourishment direct from the soil. To be absorbed and assimilated this starch must first be transformed into sugar. This chemical transformation being effected, the grain is in the condition in which the ants prefer it. Like a wine-grower who watches over the fermentation in his vat, and stops it before the wine turns sour, they stop the digestion of the starch at this stage. If we do not know how they retard germination, we know at all events how they render it impossible at this later stage. It is the young plant which absorbs the glucose, and which must therefore be destroyed; they cut off the radicle with their mandibles, and gnaw the stalk; the germ is thus suppressed. They have not yet finished their manipulations, which must enable them to preserve without further alteration the provisions which they have already rendered palatable. They bring out all their provisions to the sun, dry them, and take them back to the barns. As long as winter lasts they feed on this sweet flour. An anatomical peculiarity enables them to make the most of it; their mouth is so arranged that they can absorb solid particles and eat the albuminous powder. In this they differ from their northern kin, who are obliged to feed exclusively on juices.

I have compared the labours of these ants to those of the wine-grower. Both of them in fact utilise the chemical phenomena going on in living matter; both of them know how at a given moment to prevent the transformation from going further. Neither of them for the rest take into account the part played by diastasis and ferments. The ancestors of one as of the other have by chance found out the method, and they transmit it from generation to generation.57

Agricultural Ants. — The art of amassing stores is still more highly perfected by an Ant which inhabits North America. It is called the Pogonomyrmex barbatus, or, on account of its customs, the Agricultural Ant. It carries out a certain number of preparatory acts, and pushes foresight further than any other animal, since it looks after its property while still growing. It is grain which these insects collect, but only a single species of graminaceous grain. This choice leads them to spend great trouble on their preferred plant. They act in such a way that in the case of men we should say, purely and simply, that they were cultivating. The art of treating the earth with a view of augmenting the products which it yields is certainly of all the manifestations of human activity that which we should least expect to find among animals. It is, however, impossible otherwise to describe the conduct of Agricultural Ants. The field which they prepare is found in front of their ant-hill; it is a terrace in extent about a square metre or more; there they will allow no other plant to grow but that from which they propose to gather fruit. This latter (Aristida stricta) is rather like a grain of oats, and in taste resembles rice; in America it is called ant rice. This culture represents for these insects a much more important property than a wheat field for man. It is, in relation to their size, a forest planted with great trees, in comparison with which baobabs and sequoias are dwarfs. It is not known if the Pogonomyrmex sow their rice; Lincecum asserted that the ants actually sow the seeds, that he had seen the process going on year after year; “there can be no doubt,” he concludes, “of the fact that this particular species of grass is intentionally planted, and in farmer-like manner carefully divested of all other grasses and weeds during the time of its growth.”58 McCook is not able to accept this unqualified conclusion. “I do not believe that the ants deliberately sow a crop, as Lincecum asserts, but that they have, for some reason, found it to their advantage to permit the Aristida to grow upon their disks, while they clear off all other herbage; that the crop is seeded yearly in a natural way by droppings from the plant, or by seeds cast out by the ants, or dropped by them; that the probable reason for protecting the Aristida is the greater convenience of harvesting the seed; but, finally, that there is nothing unreasonable, nor beyond the probable capacity of the emmet intellect, in the supposition that the crop is actually sown. Simply, it is the Scotch verdict — Not proven.”59 However it may be, they certainly allow no other plant to grow in the neighbourhood of their grain, to withdraw the nourishment which they wish to reserve entirely for it. Properly speaking, they weed their field, cutting off with their jaws all the troublesome plants which appear above the soil. They pursue this labour very diligently, and no strange shoot escapes their investigations. Thus cared for, their culture flourishes, and at the epoch of maturity the grains are collected one by one and carried within. Like all harvesters, these Hymenoptera are at the mercy of a shower that may fall during the harvest. They are well aware that in this case their provisions would be damaged, and that they would run the risk of germination or decay in the barns. Therefore, on the first sunny day all the ants, as observed by Lincecum and Buckley, may be seen carrying their grains outside, only bringing them back when they have been thoroughly dried, and always leaving behind those that have sprouted.60Gardening Ants. — The Leaf-cutting Ants (Œcodoma) of tropical America are often alluded to by travellers on account of their ravages on vegetation; and they are capable of destroying whole plantations of orange, mango, and lemon trees. They climb the tree, station themselves on the edge of a leaf and make a circular incision with their scissor-like jaws; the piece of leaf, about the size of a sixpence, held vertically between the jaws, is then borne off to the formicarium. This consists of low wide mounds, in the neighbourhood of which no vegetation is allowed, probably in order that the ventilation of the underground galleries may not be interfered with.

For a long time there was considerable doubt as to the use to which the leaf-cutting ants put the leaves; some naturalists supposed they are used directly as food, others that the ants roof their underground dwellings with them. The question was set at rest by Fritz MÜller, who observed these ants in Brazil,61 and independently by Belt, who studied them in Nicaragua, and has written an interesting account of their proceedings.62 The real use of the leaves is as manure on which to grow a minute species of fungus; these ants are, in reality, mushroom growers and eaters. Belt several times exposed the underground chambers to observation and found that they were always about three parts filled with “a speckled, brown, flocculent, spongy-looking mass of a light and loosely-connected substance.” Scattered throughout these masses were the pupÆ and larvÆ, together with the smallest division of workers who do not engage in leaf-carrying, but whose duties appear to be to cut up the leaves into small fragments and to care for the young. On examination the masses proved to be composed of “minutely sub-divided pieces of leaves, withered to a brown colour, and overgrown and lightly connected together by a minute white fungus that ramified in every direction throughout it.” That they do not eat the leaves themselves was shown by the fact that near the tenanted chambers were found deserted ones filled with the refuse of leaves that had been exhausted as manure, and which served as food for the larvÆ of various beetles. There are numerous holes leading up from the underground chambers, and these are opened out or closed up, apparently in order to regulate the temperature below. Great care is also taken that the nest should be neither too dry nor too damp; if a sudden shower comes on the leaves are left near the entrance, and carried down when nearly dry; during very hot weather, on the other hand, when the leaves would be parched in a very short time, the ants only work in the cool of the day and during the night. Occasionally, inexperienced ants carry in grass and unsuitable leaves; these are invariably brought out again and thrown away.63

Domestic animals of Ants. — Following through different species the perfection reached in the art of laying up provisions for the future, we have gradually arrived at methods resembling those of Man. But a foresight still greater and nearer to his is manifested by those ants who breed and keep near them animals of different species, not for the sake of their flesh, but for certain secretions, just as man utilises the milk of the cow or the goat. Ants have true domestic animals belonging to a variety of species, but the most widely spread are the Claviger and the Aphides or plant-lice. To keep these insects at their disposal, Hymenoptera act in various ways: some, who are a little experienced, are content to take advantage of a free aphis which chance may put in their way; others shut up their cattle in stables situated in the midst of the ant-hill, or else pen them in the country at a spot where they can best find their food. These facts have long since been carefully studied and leave no room for doubt.

The Claviger testaceus is a small beetle, often met in the dwellings of ants. Nature has not been very generous on its behalf. It is blind, and its eyes are indeed altogether atrophied. The elytra are soldered at the median edge, so that it cannot spread its wings to fly. It is an animal predestined to the yoke; and for the rest its masters treat it with extreme kindness. The yellow ants, according to MÜller,64 have reduced this outcast beetle to domesticity, and it is almost a piece of good fortune for him to have lost his freedom and to have gained in exchange a shelter and a well-furnished trough. These insects are in fact cared for by their masters, who feed them by disgorging into their mouths the sweet liquids they have gathered here and there. If a nest is disturbed the ants hasten to carry their eggs and larvÆ out of danger; they display the same solicitude with regard to the Claviger, and carefully bear them to the depth of their galleries. It must not be believed that the practical insect takes so much care in order to repair the injustice of nature towards the beetle; the part of a devoted sick nurse would not suit him; he cares for the Claviger because it is his property, a capital which brings in interest in the shape of excellent sweet little drops which are good to suck.65

A yellow ant, who wishes to enjoy the result of the cares given to his pensioner, approaches it and gently caresses it with his antennÆ; the other shows signs of pleasure at this visit, and soon a pearly drop appears on the tuft of hairs at the edge of its elytra, and this the ant hastens to lick. The beetle is thus exploited and tickled by all the members of the community to which he belongs who meet him on their road. But when it has been milked two or three times it ceases to secrete. A solicitous ant arriving at this moment finds its efforts in vain, but still behaves like a good shepherd; it shows no impatience or anger towards its exhausted beast, knowing well that it is only necessary to come back a little later or to go to another member of the herd. Nor are his cares lessened by finding the source dried up. He foresees that it will still be good after repose, and if it is hungry he disgorges food for it.

Degrees of civilisation in the same species of Ants. — These facts are sufficiently marvellous in themselves, but are more surprising when we recollect that they cannot be regarded as an innate and unreflecting instinct with which all the individuals of the same species are endowed. The art of domesticating the Claviger is a stage of civilisation reached by some tribes and not by others. LespÈs66 has placed this out of doubt in the following manner. He had specimens of Lasius niger who exploited a flock of Coleoptera. Having met ants of the same species who possessed no flocks, he brought them some. At the sight of the little insects they threw themselves on them, killed them, and devoured them. If we compare these facts with those which pass in human societies, it will seem to us that these latter Hymenoptera behave like a horde of hunters in the presence of a flock of sheep, while the first have already arrived at the sheep-herding stage.

Aphis-pens and paddocks. — Ants can also keep Aphides in their homes. In this case, fearing that the adult beasts may not be able to adopt a change of surroundings and food, they bring the eggs to their nests and care for them at the same time as their own children. In time they come out and constitute a flock easy to tame. Other ants, still more intelligent, have discovered a method of holding the Aphides captive, while allowing them to enjoy their accustomed life, and to feed at will on the foods they prefer on their own favourite spots. It is sufficient for this purpose to establish barriers around a group of cattle who have themselves fixed the place of their sojourn. The Lasius niger, a skilful architect, constructs vaulted passages from his dwelling into the country. These covered roads, built with earth moistened with saliva, have various ends; some have been made in order to reach remote work sheltered from the sun, or to give concealment from enemies. Many lead to the pens of the Aphides; they reach from the anthill as far as the foot of a plant where these insects are abundant. In order to have their milkers at their disposal, without removing them from pasture, the ants make tunnels along the stalk, and enclose within it all the Aphides they meet. They thus prevent any desire for a distant ramble. But in order that the flock may not be too closely confined, the Lasius niger enlarge the galleries in places, and make a sort of chamber or stable in which the beasts may disport themselves at ease. These halls, which are proportionately very vast, are supported against the branches and leaves of the plant which bears up the walls and the vaults. The captives find themselves then with all the advantages of material life, and may be milked with every facility.67

An allied species of ant, the Lasius brunneus, lives almost entirely on the sweet secretion of large Aphides in the bark of oaks and walnut trees. The ants construct around these insects cabins made of fragments of wood, and wall them in completely so as to keep them at their own disposal.

The Myrmica also forms similar pasture lands; its system is rather less perfect than that of the Lasius, as it does not form covered galleries to reach its stables. It is content to build large earth huts around a colony. A large hole, which allows the passage of the ants, but not the escape of the flock, is formed so that they may come to milk their cows. They use the same methods we have seen practised on the Claviger, caressing the insect with their antennÆ until the sugared drop appears.68

An example is quoted which shows still greater intelligence and foresight in Ants. They have been known to repopulate their territories after an epidemic, or at least after the destruction of their Aphides. The proprietor of a tree, finding it covered with these exploited beasts, cleared it of its inconvenient guests by repeated washes; but the dispossessed Hymenoptera, considering that this pasture close to their nest was very convenient for a flock, resolved to repopulate it, and for some time these tenacious insects could be seen bringing back among the foliage Aphides captured elsewhere.69Slavery among Ants. — The custom of making slaves is widely spread in the ant world; I have already described the expeditions organised to obtain them. We will now consider the relations of these insects among themselves.

The Formica sanguinea takes possession of the eggs of the Formica fusca and rears them with its own. When the slaves reach the adult condition they live beside their masters and share their labours, for the latter work, are skilful in all tasks, and can by their own activity construct an ant-hill and keep it going. If they desire servants, it is not in order to throw all the work on them, but to have intelligent assistants. This is the primitive form of slavery as it first existed among men. It was not until later that it became modified, to become at last an institution against which the sentiment of justice arose. Other species of Ants have pushed the exploitation of slaves to a point Man has never reached. But the Formica sanguinea are companions to their helpers rather than masters, and even show them great consideration. When the colony emigrates one may see the owners of the nest, who are of larger size than the Formica fusca, take these up in their jaws and carry them the entire way.

The Amazons (Polyergus rufescens) act otherwise. Very skilful in obtaining slaves and powerfully armed for triumphant raids, their nests always contain legions of servants, and the custom of being waited upon has become so impressed on the race by heredity that it is an instinct stronger even than personal preservation. The master ant has not only lost the taste and the idea of work, but even the habit of feeding himself, and would die of hunger beside a pile of honey or sugar if a grey ant was not there to put it into his mouth. Thus Huber, the earliest accurate observer of these ants, enclosed thirty Amazons with several pupÆ and larvÆ of their own species, and twenty negro pupÆ, in a glass box, the bottom of which was covered with a thick layer of earth; honey was given to them, so that, although cut off from their auxiliaries, the Amazons had both shelter and food. At first they appeared to pay some little attention to the young; this soon ceased, and they neither traced out a dwelling nor took any food; in two days one-half died of hunger, and the other remained weak and languid. Commiserating their condition, he gave them one of their black companions. This little creature, unassisted, formed a chamber in the earth, gathered together the larvÆ, put everything into complete order, and preserved the lives of those which were about to perish.

All their industry is expended in the acquisition of captives. The Polyergus avoid introducing into their houses adults who would not become reconciled to the loss of liberty, and would prefer to die rather than work for others. They carry off the larvÆ of Formica fusca and Formica cunicularia. When brought into the ant-hill these larvÆ are placed in the jaws of slaves of their own species, who care for them; they are born captives, and have neither the regret nor the idea of a free life. Among the Amazons the slaves undertake every labour; it is they who build and who care for the larvÆ of their masters, as well as those carried away in expeditions. They have also complicated personal services towards the Polyergus. They bring them food, lick off the dust from their hairs, clean them, carry them from one place to another, if there is need to emigrate, although they themselves are much smaller. The masters, by force of losing interest in work, lose also their votes when it is a question of taking a resolution concerning the whole colony. The servants act on their own initiative and their own responsibility, direct constructions according to their own ideas, and even in grave concerns, such as emigration, the idle masters do not seem to be consulted. The workers deliberate among themselves, and having come to a decision, proceed to execute it. They transport the household goods, the eggs, the future of the city, and the Amazons who have become its parasites. It is a most curious fact that the slaves should submit to this precarious fate when their masters are absolutely dependent on them. It is just to add that the robust mandibles of the latter may contribute to preserve the position they enjoy.70