small segments (Fig. 53, B, C, b, c) forming nodes or knots, of almost any shape. The articulations between these segments are of the most perfect description. In many ants these parts bear highly developed stridulating organs, and the delicacy and perfection B A FIG. 57.-Combs and brushes on front leg of an ant, Dinoponera grandis (tip of tibia, bearing the comb-like spur, and the base of the first joint of the tarsus; cf. fig. 75). A, Inner, B, outer aspect. of the articulations allow the parts to be The legs of ants are elongate, except in a few forms; the Cryptocerini and the males of Dorylides being the most conspicuous exceptions. The tarsi are five-jointed, the basal joint being disproportionately elongate, so that in use it acts in many species as if it were a portion of the tibia, the other four joints forming the functional foot. The front tibiae are furnished with a beautiful combing apparatus (Fig. 57). Features of Ant-life. In order that the reader may realise the nature of ant-life we may briefly recount its more usual and general features. Numerous eggs are produced in a nest by one or more queens, and are taken care of by workers. These eggs hatch and produce helpless maggots, of which great care is taken by the workers. These nurses feed their charges from their own mouths, and keep the helpless creatures in a fitting state by transporting them to various chambers in conformity with changes of temperature, humidity, and so on. When full grown the maggots change to pupae. In some species the maggots form cocoons for themselves, but in others this is not the case, and the pupae are naked.1 After a brief period of 1 The pupae and cocoons of ants are usually called by the uninstructed, "ants' eggs." In this country they are used as food for pheasants. pupal life a metamorphosis into the perfect Insect occurs. The creatures then disclosed may be either. winged or wingless; the wingless are the workers and soldiers-imperfect females-the winged are males or females fully developed. The workers remain in or near the nest they were produced in, but the winged individuals rise into the air for a nuptial flight, often in great numbers, and couple. When this is accomplished the male speedily dies, but the females cast their wings and are ready to enter on a long life devoted to the production of eggs. From this account it will be gathered that males are only found in the nests for a very short time; the great communities consisting at other periods entirely of the two kinds of females and of young. The imperfect females are themselves in some species of various kinds; each kind being restricted, more or less completely, to a distinct kind of duty. No Insects are more familiar to us than ants; in warm countries some of them even invade the habitations of man, or establish their communities in immediate proximity to his dwellings. Their industry and pertinacity have, even in remote ages, attracted the attention and admiration of serious men; some of whom we need scarcely mention Solomon as amongst themhave not hesitated to point out these little creatures as worthy of imitation by that most self-complacent of all the species of animals, Homo sapiens. Observation has revealed most remarkable phenomena in the lives of these Insects. Indeed, we can scarcely avoid the conclusion that they have acquired in many respects the art of living together in societies more perfectly than our own species has, and that they have anticipated us in the acquisition of some of the industries and arts that greatly facilitate social life. The lives of individual ants extend over a considerable number of years-in the case of certain species at any rate so that the competence of the individual may be developed to a considerable extent by exercise; and one generation may communicate to a younger one by example the arts of living by which it has itself profited. The prolonged life of ants, their existence in the perfect state at all seasons, and the highly social life they lead are facts of the greatest biological importance, and are those that we should expect to be accompanied by greater and wider competence than is usually exhibited. by Insects. There can indeed be little doubt that ants are really not only the "highest" structurally or mechanically of all Insects, but also the most efficient. There is an American saying to the effect that the ant is the ruler of Brazil. We must add a word of qualification; the competence of the ant is not like that of man. It is devoted to the welfare of the species rather than to that of the individual, which is, as it were, sacrificed or specialised for the benefit of the community. The distinctions between the sexes in their powers or capacities are astonishing, and those between the various forms of one sex are also great. The difference between different species is extreme; we have, in fact, the most imperfect forms of social evolution coexisting, even locally, with the most evolute. These facts render it extremely difficult for us to appreciate the ant; the limitations of efficiency displayed by the individual being in some cases extreme, while observation seems to elicit contradictory facts. About two thousand species are already known, and it is pretty certain that the number will reach at least five thousand. Before passing to the consideration of a selection from what has been ascertained as to the varieties of form and of habits of ants we will deal briefly with their habitations and polymorphism, reserving some remarks as to their associations with other Insects to the conclusion of this chapter. Nests. Ants differ greatly from the other Social Hymenoptera in the nature of their habitations. The social bees construct cells of wax crowded together in large numbers, and the wasps do the like with paper; the eggs and young being placed, each one in a separate cell, the combinations of which form a comb. Ants have, however, a totally different system; no comb is constructed, and the larvae are not placed in cells, but are kept in masses and are moved about from place to place as the necessities of temperature, air, humidity and other requirements prompt. The habitations of ants are in all cases irregular chambers, of which there is often a multiplicity connected by galleries, and they sometimes form a large system extending over a considerable area. Thus the habitations of ants are more like those of the Termites than those of their own allies among the Hymenoptera. They are chiefly remarkable for their great variety, and for the skilful manner in which they are adapted by their little artificers to particular conditions. The most usual form in Europe, is a number of subterranean chambers, often under the shelter of a stone, and connected by galleries. It is of course very difficult to trace exactly the details of such a work, because when excavations are made for the purposes of examination, the construction becomes destroyed; it is known, however, that some of these systems extend to a considerable depth in the earth, it is said to as much as nine feet, and it is thought the object of this is to have access to sufficiently moist earth, for ants are most sensitive to variations in the amount of moisture; a quite dry atmosphere is in the case of many species very speedily fatal. This system of underground labyrinths is sometimes accompanied by above-ground buildings consisting of earth more or less firmly cemented together by the ants; this sort of dwelling is most frequently adopted when the soil in which the nests are placed is sandy; it is probable that the earth is in such cases fastened together by means of a cement produced by the salivary glands of the ants, but this has not been determined with certainty; vaulted galleries or tunnels of this kind are constructed by many species of ants in order to enable them to approach desired objects. FIG. 58.-Portion of combined nest of Formica fusca and Solenopsis fugax. (After Forel.) 3. ff', Chambers of Formica, recognisable by the coarser shading: s, s', chambers of the Solenopsis (with finer shading); s", opening in one of the chambers, the entrance to one of the galleries that connects the chambers of the Solenopsis; u, walls forming the foundations of the nest and the limits of the chambers. In South America Camponotus rufipes and other species that habitually dwell in stumps, in certain districts where they are liable to inundations, build also nests of a different nature on trees for refuge during the floods. In Europe, a little robber-ant, Solenopsis fugax, constructs its dwelling in combination with that of Formica fusca (Fig. 58), in such a manner that its chambers cannot, on account of the small size of the orifices, be entered by the much larger Formica. Hence the robber obtains an easy living at the expense of the larger species. The Sauba or Sauva ants of South America (the genus Atta of some, Oecodoma of other authors) appear to be most proficient in the art of sub terranean mining. Their systems of tunnels and nests are known to extend through many square yards of earth, and it is said on the authority of Hamlet Clark that one species tunnelled under the bed of the river Parahyba at a spot where it was as broad as the Thames at London Bridge. A considerable number of ants, instead of mining in the ground, form chambers in wood; these are usually very close to one another, because, the space being limited, galleries cannot be indulged in. Camponotus ligniperdus in Europe, and C. pennsylvanicus in North America, work in this way. Its Our British Lasius fuliginosus lives in decayed wood. chambers are said by Forel to consist of a paper-like substance made from small fragments of wood. Cryptocerus burrows in branches. Colobopsis lives in a similar manner, and Forel informs us that a worker with a large head is kept stationed within the entrance, its great head acting as a stopper; when it sees a nest-fellow desirous of entering the nest, this animated and intelligent front-door then retreats a little so as to make room for ingress of the friend. Forel has observed that in the tropics of America a large number of species of ants live in the stems of grass. There is also quite a fauna of ants dwelling in hollow thorns, in spines, on trees or bushes, or in dried parts of pithy plants; and the tropics also furnish a number of species that make nests of delicate paper, or that spin together by means of silk the leaves of trees. One eastern species-Polyrhachis spinigera-fabricates a gauze-like web of silk, with which it lines a subterranean chamber after the manner of a trap-door spider. FIG. 59.-Ant-plant, Hydnophytum montanum. Java. (After Forel.) Some species of ants appear to find both food and shelter |