Page:Encyclopædia Britannica, Ninth Edition, v. 2.djvu/105

Rh communities. This result he achieved by means of an apparatus which enabled him to view the interior of the nest. Many facts have been added to the history of ants since 1810; the list of works and treatises upon this and allied entomological pursuits having been largely increased, especially of late years. The constitution of an ant-community may be readily appreciated; but it is, at the same time, important to note the distinctions between the various groups or sects into which the curious colony is divided. A threefold distinction of sex, resulting in the production of three kinds of individual forms, is to be perceived in the ant-colony, as well as among other hymenopterous insects (e.g. bees). These three grades of individuals are known respectively as males, females, and neuters. The males and females are winged, the former retaining their wings throughout life, and the latter losing these organs after the pairing is over. During the summer the winged males and females are produced in large numbers, and they soon leave the nest to take their "nuptial flight" in the air, in the course of which the females are impregnated. The function of the male ants having been thus performed, they die; the females, after impregnation, lose their wings; and whilst in this comparatively helpless state they are conveyed by the neuters to new situations, where they become the founders of fresh colonies.

EB9 - Ant - Fig 1.png. 1.—Wood Ant (Formica rufa). 1, Female; 2, Male; 3, Neuter.

Each fertile female or " queen " is carefully attended by a retinue of " neuters," the latter being simply females the sexual organs of which are undeveloped. The curious experiments of entomologists have proved that, in all probability, the cause of this differentiation of sex is dependenl upon the nature of the food with which during the larva state the ant is fed. Exempted thus from all sexua functions, the duties of the neuters are confined to the performance of all the offices which contribute to, or are connected with, the welfare and labour of the ant-community. They thus not only construct and build the nest or home, and keep it in constant and assiduous repair, bul they are also the providers of food and sustenance for the community; and they act the part of nurses, in that they carefully attend to the hatching, nutrition, and rearing of the young. They are also the defenders of the colony, ir that they protect the nest and its inmates from the attack: and assaults of nearly-related enemies or foreign foes. Ir connection with the defence of the ant-colony, certaii species possess peculiar neuters, termed "soldiers," upon which the care and protection of the community more especially devolve. These "soldiers " are provided with large mandibles or biting-jaws, which constitute efficien organs of offence or defence; and they are distiuguishec from the ordinary neuters by several characteristics ir addition to this larger development of the jaws. Regarding the more intimate structural differences which have been ascertained to exist between the various member of the ant-community, it may be remarked that the antenna of the male ants possess thirteen joints each, and those of the female twelve. The antennae of the neuters are com posed of twelve joints. The abdomen of the male ant con sists of seven joints, and that of the female and neuter o six. The mandibles or large jaws of the female and neute Qiits are larger than those of the males, and are frequently found to be serrated or even hooked at their extremities. the external sexual organs of the neuters correspond to hose of the females, although, as already remarked, the sssential internal reproductive organs are wholly unde veloped in the neuter ants; and to this most important distinction there is added the absence of wings, the neuters oeing thus distinguished from the females by a variety of characters, while the near relation is at the same time shown of the one series of truly sexual forms to those in which the sex is undeveloped. The neuters, it may lastly ba remarked, conform to the female characteristics, in having the abdomen provided with a sting, the male ants being destitute of this appendage. The nervous system of the ants conforms to the ordinary insect-type; but in these and other insect forms, we find the slighest development of those faculties to which the general name of Instinct is applied. By instinctive acts, in their simplest sense, we mean those acts which an animal per forms chiefly from impressions made by surrounding objects upon its nervous or sensory apparatus. These are very different in character and origin from the actions of the higher vertebrate animals, in which the independent faculty of mind operates as the direct source of action, in place of the surrounding circumstances of the lower form. Thus, in the case of ants, bees, &c., wonderful as their operations may appear, and regular and methodical as the manner in which they are performed may seem, it will be found that a marked uniformity and likeness of conditions exist, which tend to produce a corresponding similarity of effects. The same external conditions thus tend to induce undeviatingly similar series of phenomena, and under the operation of these acts the animal exercising them may justly be compared to an automatic machine, or to a piece of mechanism, self-directing only in so far as it is directed by external .circumstances and outside conditions. Hence we find certain species of ants or bees invariably constructing similar series of cells or habitations, and engaging in the same labours as their predecessors, which labours or operations will be faithfully and exactly repeated by succeeding generations. And the automatic and me chanical nature of instinctive acts may be clearly viewed when we contrast them in their essential nature with the directing intelligence and guiding impulse of mind, as we find these qualities exercised in the highest vertebrates. In the latter case, the mental impulse itself directs alike the physical and psychical operations, and so far from the animal being merely automatic, it assumes the higher phase of nervous action involved in self-originating mental impulse. The actions of the intelligent being are selfdetermined: those of the instinctive being originate from the outer world. Through the higher nervous centres the intelligent being first appreciates the outward circum stances, and then reacts upon them; the nervous centres of the lower being are, in the first instance, acted upon by the outer world, and then in their turn react upon the organism. Lastly, and in accordance with the more per fect appreciation of external objects through sensations and perceptions, we have to note in the higher being the operation of the educative power we entitle experience. The ant or bee, when first introduced into the special sphere of its labours, assumes its functions, and performs its duties as perfectly as if it had been engaged in their perform ance for a lengthened period. And the long-continued performance of these duties will in no degree tend to make the ant or bee a more perfect or more skilful worker than when the performance of the duties first commenced. Here, again, we observe the operation of the automatic powers; the lower animal, like the perfected machine, operates at once and without any previous experience as perfectly as after a lengthened period of working. But,