Encyclopædia Britannica, Ninth Edition/Ant

by Andrew Wilson

ANT. The insects included under this name are divisible into two distinct groups, which exhibit important differences not only in structure but also in habits. The familiar ant (Formica), found in Britain and Europe generally, belongs to an order of insects known as the Hymenoptera, of which division the bees, wasps, hornets, are also well-known examples. But the Termites, or white ants insects which also live in social communities, and which inhabit tropical regions belong to a different order, that of the Neurop- terous insects, and exhibit differences in several important respects from the ordinary ants. To both species or kinds of these forms it will be necessary to direct attention, and the familiar ants naturally fall to be considered first.

The Hymenopterous insects are distinguished by the possession of four membranous wings, although in certain exceptional instances as among certain members of the ant community the wings may be wanting. The organs of the mouth are partly fitted for mastication by the development of jaws, and partly for suctorial purposes by the possession of a proboscis or " antlia." The females of this order generally possess a terminal abdominal append age, forming a " sting " (aculeus), or which may be used in the deposition of the eggs, when it is termed an ovipositor. The Hymenoptera, besides, undergo a " complete " meta morphosis, that is, in their passage from the egg towards adult or mature existence they appear first as grubs, or larvae, then are enclosed in a pupa-case, and finally appear as the perfect, and generally winged insect, or "imago." The Hymenoptera exhibit, perhaps, the most remarkable development among insects of the faculty of instinct, and constitute excellent examples of so-called "social" insects, living in communities regulated by definite laws, each mem ber of the society bearing a separate and well-defined part in the organisation and arrangement of the colony at large.

From the earliest times ants have attracted the attention, not only of naturalists, but of philosophers and poets. The ancients were familiar with many of the phenomena characteristic of the ant colony. Aristotle and Pliny, for example, inform us that the labours of ants are regulated in a great measure by the phases of the moon. Pliny also makes mention of a species which he alleges is found in Northern India, which were said to equal Egyptian wolves in size, and were supposed to occupy themselves in digging gold from the bowels of the earth, whilst the inhabitants of the country were said to rob the ants in summer of their accumulated winter treasures.

The harvesting and grain-storing habits of ants, so familiar to the popular reader, were at first supposed to be common to all species of ants; but this view has been abun dantly proved to be erroneous, whilst the opposite extreme of asserting that no species practise these habits is to be viewed as equally incorrect. In many cases it is probable that observers have been deceived into the supposition that certain species of ants really carried grains of corn in their mouths, whereas the so-called corn grains of these species were in reality the cocoons or pupa3-cases containing the young and immature forms. And whilst most species of ants are granivorous, or vegetable feeders, certain species are as decidedly carnivorous. These latter kinds do not, therefore, participate in the frugal and industrious habits of their allies.

The bibliography of ants is very extensive. Dr King, in the 23rd number of the Philosophical Transactions, described the form of the eggs and of the larvse, and also the habits of ants in reference to their care of their young. Leeuwenhoeck, the Dutch naturalist, traced the successive stages of development in the ants, and demon strated the egg, "larva," "pupa," and "imago," or perfect insect. Swammerdam, with the application of the micro scope, further advanced the knowledge of the development and structure of the ants ; and Linnaeus (Memoirs of the Royal Academy of Sciences of /Stockholm) ascertained many facts relative to the reproduction of these forms, and determined that the winged ants are those which alone exercise the generative functions. A Mr Gould published An Account of English Ants, of which work a notice by the Rev. Dr Miles is given in the Philosophical Transac tions for 1747. This account, excellent in many respects, is nevertheless erroneous in certain points, the result of following too closely the analogy presumed to exist between bees and ants. Geoffrey (Hwtoire des Insectes qui se trouvent aux Environs de Paris], a good naturalist otherwise, is a bad authority on the subject of ants. The most complete series of observations on ants, which appeared among the earlier accounts of these forms, are those of De Geer, a Swedish entomologist (Memoires pour servir a VHistoire des Insectes), an observer on whose fidelity the utmost reliance may be placed. Olivier, in the Encyc lopedic Methodique (article Fourmi], summarised the know- ledge of his own and of preceding times, and described a few new species of ants ; and Bonnet, in his Observations sur les Insectes (vol. ii.),has given us some interesting, though by no means extensive information regarding the habits of ants. The "sugar-ant" (?) forms the subject of a memoir in the Philosophical Transactions for 1790, this latter species having caused much havoc among the sugar-plan tations of Grenada over a period of ten years. Latreille, a amous entomologist, in his special monograph (Histoire Naturelle des Fourmis), published at Paris in 1802, gave the most succinct and accurate account of the ant-tribe which had appeared up to that date. His description of the structure and classification of these insects is remark ably clear, and he fully describes one hundred species inown to himself, and mentions twenty-four species which was enabled to describe from the reports of others. He distributed these species among nine families, selecting as .he bases of his classification the situation and structure of he " antennoe " or "feelers," and the disposition of the tbdominal scales.

The habits of ants receive the fullest attention at the

lands of Pierre Huber of Geneva, who in a treatise (Traits les Mceurs des Fourmis Indigenes) published in 1810, gave a very interesting, lucid, and valuable account of his

native ants, drawn from actual observation of the nests and 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.

Fig. 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, in the higher operations directed by intelligence, the being

acquires in a gradual manner, and only after a lengthened experience, the perfect manner of working. In the one case instinct incites the being automatically, or through the excitory outward impressions, to perform the acts; in the other, an intelligent mind first appreciates the impres sions, and, through the educative training of experience, is enabled to perform the acts, and to understand in a greater

or less degree the reasons which prompt and justify them.

Apart from the possession of high instincts, however, we find ants, in common with many other insects, to be pos sessed of very perfect senses. In addition to the large compound eyes with which most insects are provided, they possess simple organs of vision. The sense of smell also appears to be represented in the ants and insects generally, but the seat of this sense has not been well or satisfactorily determined. Judging from analogy, however, the olfactory apparatus has been supposed to reside in the basal joints of the feelers or antennae. Ants have been long observed to follow accurately the track of their companions. Bonnet concluded that they were enabled to follow up this line of march by their scent, and in proof of this he repeatedly drew his finger at various parts across the line of march. The ants, on arriving at the interrupted spots, seemed to lose scent, and directed their steps in an irregular and hesitating manner, but having once crossed the interrupted space of the finger track, they resumed their journey once more in a regular manner along the line of march. Latreille, with the view of ascertaining if the sense of smell resided in the antennas, cut off these organs in several ants, when he found that they appeared to lose their way, and to be incapable of directing their further steps. It may, how ever, on obvious grounds be doubted whether this experi ment may be deemed at all satisfactory or conclusive on the point. In this experiment it was noticed that the neighbouring ants appeared to observe the distress of their mutilated companions, and they seemed to stanch the wounds of the sufferers by an application of the organs of the mouth to the wounded surface.

The antennæ in insects are certainly the organs of touch, but in ants these organs appear to subserve some undeter mined function, in that through their agency communication may be made from one ant to the other. M. Huber was so strongly impressed with this latter fact, that he applied the term langage antennal to the intercourse which he sup posed took place between ants through the media of the antennae. For example, by each ant striking its head against its neighbour, and by the transmission of this impulse, the whole ant-community appeared to be warned of danger, and in other ways, but chiefly through the antennae, the sense of danger appears to be appreciated by each member of the colony.

The food of ants has formed a debatable point ever since the attention of naturalists was directed to the investigation of their economy. As already remarked, many species are truly carnivorous, and prey upon the soft parts of other insects, and particularly of larva?, which they are enabled to seize and capture with little danger and trouble. The well- known partiality of ants for animal food is taken advantage of by those who wish to obtain the hard parts or skeletons of animal forms ; since by placing an animal body within reach of an ant-colony, the soft parts are gradually eaten away, and the harder portions are left intact. In tropical climates, rats, mice, and poultry, even in a living state, are said to succumb to the attack of these creatures; and man himself, as related by Prdvost in his Histoire General des Voyages, is even subject to the attacks of ants. Prdvost relates that an Italian missionary in Congo was awakened from sleep by his negroes, with the intelligence that an immense horde of ants was invading his house. Before he could rise they had already covered his legs, and the floor of his house was carpeted by a thick layer of the invading forms. Fire seemed to be the only preventive to their onward march ; and it was stated that cows were known to be devoured in their stalls by these creatures. These remarks may be viewed as applying more particularly to the white ants or termites, of which an account will be given, afterwards. For sugar ants seem to have a special pre dilection ; and they appear not only to obtain the saccharine matter from vegetables, but also to abstract it from animal sources. The aphides, or plant lice, become in this way the subjects of very extraordinary attentions on the part of ants. The plant lice possess a glandular structure, situated at the extremity of the abdomen, which communicates with the external surface by two small ducts. This gland- secretes a sweet or saccharine liquid of viscous nature, of which ants are extremely fond, and the aphides appear to be literally " milked " by their smaller neighbours. The antennae of the ants in this case also appear to be the media of intercourse between the aphides and themselves, and by touching the abdomen of the plant lice with the antenna?, a drop of the saccharine liquid exudes from the gland, which is eagerly seized upon by the ants ; and in this fashion the milking process is continued until the ant is satisfied. The aphides, in this instance, appear voluntarily to surrender themselves for the purpose of affording the saccharine matter; but it has been also alleged that certain species of ants keep aphides within their nests for the pur pose of affording the desired matter. Whether or not this alleged domestication of the aphides by ants is to be deemed worthy of belief yet remains to be proved. A single aphis may be occasionally seen surrounded by three or four ants, the latter ordinarily finding the aphides on the leaves of plants and in their natural habitat. The association of ants and aphides, strange as it may seem, is not, how ever, without its parallels in the history of the ant-colony. Thus wood-lice are not infrequently found as apparently normal guests within the ant-nest; and Siva of Pisa observed a species of grasshopper, to which he has given the name Gryllus myrmecophilus, which inhabits the nest of an Italian ant. The ant-nest, in fact, appears to be the normal: habitation of this grasshopper.

The ant-nest forms a very interesting subject for consideration, and the various groups of ants differ widely in the outward form and internal plan according to which the nests are constructed, as well as in the materials of which the habitations are built. Clay, earth, and vegetable matters form the chief sources of supply, and excavations in the ground, or erections above ground, in trees, walls, and house-roofs, may be mentioned as the most common situations for the nests. The internal arrangement also varies even to a greater extent than the external appearance or materials. The general plan of the nest shows an arrangement of flats or stories, connected throughout by passages, and supported by definite pillars or partitions. The chief ends and objects in the construction of the nest appear to be directed to the preservation of the larva?, and to their protection from changes of temperature. During the night the larva? are placed in the furthest chambers of the nest, the entrance to the nest being carefully secured for warmth and for ensuring protection from the raids of enemies. In the morning the larva? are transferred by the diligent neuters to the outer chambers, to which the sun s heat has access ; or they may even be exposed directly to the sun. A change of temperature or weather is sufficient to set the watchful neuters on the alert, and to cause them to hurry the larvaa to the inner recesses of the abode, where they may be safely protected from the variable effects of the climate.

Some of the most curious and extraordinary traits in ant-character relate to the acquiring by certain ants (e.g. Amazon- ants) of the pupae or immature young of other species, anc the training and subjection of these pupae as slaves anc servitors. Eegular raids and forays appear to be made by the slave-making ants upon the nests of certain species, the pupae of which, are captured, and when developed broughl into bondage and subjection to the captors.

No closer imitation of the ways of man could well be found in the entire animal economy; and the circumstances of these curious cases have been so thoroughly investigated that the matter is placed above the possibility of doubt or error. The relative position of the masters and slaves varies greatly, the extreme of hard servitorship being seen in some cases, whilst in other cases the position of the slaves is much easier. The slaves of Formica sanguined are aided by their masters in the work of the colony. But in the case of Formica rufescens the labours of the slaves are greatly increased, the entire work of the community devolving upon the unfortunate captives, and the neuters, laborious in other species, being merely employed in the duty of capturing fresh servitors. This latter trait also appears among the Amazon-ants, which literally stir neither "hand nor foot," nor make any effort to help themselves, but are waited upon and attended in the most devoted manner by their willing serfs. The slave making forays are by no means invariably destitute of bloodshed or warfare, and frequent and hot combats appear to be engaged in between the would-be masters and the species of intended slaves. Once captured, developed, and domiciled within the nests of their masters, the slave-ants appear to be thoroughly at home, and no effort at insurrection or attempt to gain their freedom appears ever to be made. The early state of development in which the pupae are generally captured, would necessarily favour the complete domestication of the captured ants within the home of the slave-making community; and the ants appear to possess and exhibit the greatest care and solicitation for the welfare of their serfs, the slaves being carried in the mouths of their owners when the latter shift their abode, or undertake any expedition leading them from home.

From the accounts of Messrs Bates and Belt, we gain some curious and interesting information regarding species of ants peculiar to South and Central America, which ex hibit marked differences in habits from all British or even other foreign species. Chief among these South American ants are the Foraging Ants (Eciton], of which there are several distinct species. These ants are truly carnivorous in their tastes, and ravage whole districts, their march being regarded with terror by the natives of Central America. Mr Bates tells us that different species have different modes, of marching, by which they may be recog nised. The Ecitons in Nicaragua are termed "Army Ants," and they appear regularly to change their hunting-grounds in quest of food. Their community comprises males and females, and two kinds of neuters or workers a "workermajor," or large-headed worker, and a small-headed kind, termed the " worker-minors." The former kind are noted for their elongated jaws; and in some species these forms are denominated " soldiers/ their peculiar office being the protection of the community from, the attacks of enemies, or the making forays on the nests of other species, or upon other animals. The habit the Ecitons have of hunting in regular organised bands, distinguishes them from other and more familiar British species (e.g., Myrmica, the Red Stinging Ant of Britain), which are predatory, but hunt in an irregular and ill-defined manner. One of the bestdefined species of foraging ants is the Eciton predator, a small species which hunts in dense hordes, and marches rapidly over a territory. A moving phalanx of this species will extend over from 4 to 6 square yards; and any unwary insect meeting with, or falling into the serried ranks, is soon torn to pieces and devoured. Eciton kamata hunts both in dense masses or in detached columns. The nature of the prey appears to regulate the mode of march. Thus, when proceeding in columns, Mr Belt found that the Eciton Jiamata was in search of the nests of another ant (Ilypoclinea), the larvas and pupae of which are seized by the Ecitons for the purpose of being brought up as slaves, in accordance with the habits already alluded to. The Hypoclineas rush out on being attacked, bearing their pupae and larvae in their jaws; but the Ecitons at once seize the young ants, although they never appear to injure the parent Hypoclineas. The latter appear a cowardly race, as they make no effort at self-defence, their habits leading them chiefly to milk aphides, which they desert at ouce on seeing another and even smaller species of ant approach. Birds and opossums are terrified, as well as insects, at the Foraging Ants, and frequently fall victims to the deter mined onslaught of the little furies.

Fig. 2.—Leaf-cutting and Foraging Ants. 1, Œcodoma cephalus; 2, Eciton drepanophora; 3, Eciton erratica.

The other species of Ecitons comprise Eciton rapax, the largest of the race, the body of which is half-an-inch in length; Eciton legionis, famed for its ravages on other species of ants (Formicce); Eciton harnata and E. drepanopliora, nearly related species; and the so-called Blind Ecitons, thus named from, the imperfect condition of the eyes. The E. vastator and E. erratica, species of blind Ecitons, proceed on their raids by means of covered roads or ways, which are excavated and formed in front at a rate corresponding to the advance of the army.

Some interesting information regarding the senses and instincts of the Foraging Ants appears to corroborate the opinions of some earlier observers, already alluded to, on the subject. About a dozen individuals of Eciton Jiamata were observed to assemble together, as if in consultation, in a tramway excavation in Nicaragua. One ant suddenly left the assembly, and ran up the perpendicular side of the cutting. The example of this first ant was followed by several others, which ran after the first ant for a short distance, then returned, and again proceeded for a farther distance along the track of the first. The object of this proceeding was to make the track readily determinable by the succeeding travellers, and the route of the first individual was unerringly followed by the others, who were at long distances behind. A portion of the trail was removed, when the ants appeared at fault, and occupied themselves in making detours until they again hit upon the interrupted track. On arriving at the top of the excavation, a suitable spot for hunting was descried, when the information appeared to be quickly communicated to those that were aelow, and the whole army rushed upwards in obedience to the behest of the scouts. All the Foraging Ants are migratory in habits, and appear to possess no fixed place of abode, but shift their camp at intervals of from four to six or more days. The temporary abode is found in hollow trees, or under fallen trunks. An Eciton, intentionally imprisoned beneath a stone, was discovered by a companion, who at once informed his neighbours. The other ants then came to the rescue; and by biting at the stone, trying to move it, and seizing the prisoned ant by the legs, they, by their united efforts, set their companion free. An ant embedded in clay, with only the points of the antennae protruding, was discovered by Ms neighbours, and soon disentombed. And in cases where the efforts of one ant have been inadequate to release a comrade placed in peril, the others were duly informed of the fact, and hurried to assist their less fortunate neighbour. In crossing a crumbling slope, which was gradually disintegrating under the passage of the ant-army, a portion of the band, by adhering to each other, formed a solid, pathway, over which the others passed safely. A twig formed a bridge across a small rill; but this proving insufficient and too narrow for the transit of the army, it was widened by ants clinging to each side of the twig, and in this way the track was broadened sufficiently to admit of the easy passage of the mass. Such acts would appear to lie beyond the category of purely instinctive processes, since they appear to involve an adaptation of faculties to special cases, and result in special actions being instituted, and thus bear some resem blance to what we familiarly see involved in the process of reasoning characteristic of man's mental powers. The more ordinary operations of ant-life are purely instinctive, as has been already shown; but it may be a matter for considera tion if the theory of some naturalists, that the higher development of instinctive powers is akin to reason itself, may not be tenable. Such instances as these just given of the curious and extraordinary acts of the Foraging Ants may serve to show from what circumstances the theory obtains support. Houzeau, in particular, among recent writers, adopts analogous views to these, and maintains that the ants most nearly approach man in the arrangement and general nature of their social existence and condition.

The Leaf-cutting Ants ((Ecodomd) are noted pests of central and tropical America; and, as is implied by their name, commit fearful havoc among trees, laboriously and persistently carrying off in their mouths, piece by piece, the foliage of trees and shrubs. The orange, lemon, and mango trees in particular have suffered from their attacks. Carbolic acid has been tried with success as a remedy against these ants, the use of this antiseptic killing large numbers; and corrosive sublimate in powder, sprinkled across their paths, has a deadly effect upon the leaf-cutters. Coal tar has also been employed against them. Gigantic black ants, averaging an inch in length, arc found in Central America. They are notable as being solitary in their habits, and possess well-developed eyes and formidable stings. These forms contrast with the gregarious and social ants, in which the eyes are com paratively weak, or may be rudimentary.

Certain curious little ants (Pseudomyrma bicolor) inhabit the hollow thorns of the " bull's horn " acacia of Central America. The horn-like thorns form the nest, the aperture being situated near the tip of the thorn. These ants pre serve the plant from the attack of the Leaf-cutting Ants, and also from mammals feeding upon it. The ants obtain a supply of food from the plant, in the shape of a honeylike secretion, found in a gland situated at the base of the leaflets. Protected by, and at the same time protecting the plant, the intimate relations between the acacia and the ants may be argued to possess a deeper significance than relates to a merely casual or chance connection. The Cecropia, or trumpet tree of Central America, is ten anted by ants, which obtain a sweet fluid, through the agency of brown scale-insects (Coccidce), kept by them in the cells of the trunk. This recalls the case of the aphides, or ordinary plant lice, the ants sucking the fluid from the scale-insects through a dorsal or back-pore. The queen-ant in her royal cell is attended by a special bevy of Ooccidce, who supply her with the requisite food. The Coccidce in America take the place of the European aphides as ant-cows, but the tropical ants appear to attach themselves to other insects also. Thus, the leaf-hoppers (Hembracis) are attended by ants, for the sake of the honey which the larvae exude. Those insects which are attended by ants are protected from the attacks of other animal forms; and the shelter given to the ants thus serves to protect the tree or shrub, and to save it from becoming exterminated.

The " soldier ants," referred to in the foregoing account of the Foraging Ants, are not peculiar to that race, many other species also possessing " soldiers." These forms, as has been already stated, appear to be merely neuters which have the jaws very largely developed, for the protection of the true neuters or workers, and for the defence of the nest generally. This further subdivision of the ant-community would seem to indicate an additional approach to the social arrangements which characterise the human state.

The reproduction and development of the ordinary ants may be very briefly touched upon in the present notice. The impregnation of the females in their aerial nuptial flight has been already alluded to, as also has the death of the males after the congress. The impregnated females are conveyed to the nest, and the deposition of eggs is pro ceeded with, the young forms being tended through their larvae and pupae stages by the assiduous neuters. Unlike the bees, several female ants may inhabit the same nest; and the swarming or exodus of the young ants, so far from having for its one and essential object the formation of a new colony, appears to be simply devoted to further reproductive measures. Thus, those that leave the nest are the fresh males and females, the sexual history of which has already been traced; and the nest thus remains a more or less permanent institution, changing its inmates only in part, and in exceptional circumstances alone giving origin to a new and independent colony.

The stings with which the neuters and females are armed constitute formidable organs of defence. The poison, to which the violent or painful effects of the sting are due, appears to consist of a definite chemical organic compound, the chief acid of which is known by the appropriate name of formic acid, the formula for this compound being CH 2 O 2 . Formic acid is also found in the glands attached to the pointed hairs of stinging-nettles. This acid, in itself possessing irritant qualities of a high order, also appears capable of producing even more serious effects when manipulated by chemical means.

Fig. 3.—Ant-lion (Myrmeleo formicaleo).

The ant-colony, powerful as we have seen it to be, and well protected as it undoubtedly is, is nevertheless subject to the attacks of enemies which wage a successful war against it. Certain species of ants appear to be more subject than others to the attack of such higher forms as the mammalian ant-eaters (Echidna and Myrmecophagidce) and armadillos, as well as to the onslaught of the insect ant-lion (Myrmeleo). The latter literally digs a pit for his victim, in the bottom of which he lies securely hidden, ready to devour any unwary ant which may chance to tumble in. And even where the victim is not within actual reach of the Myrmeleo, the latter by means of a shower of sand-particles frequently succeeds in causing it to fall into the snare. Several substances which have a noxious effect upon the ant-colony have been already mentioned. Thus carbolic acid and corrosive sublimate appear to affect the ant-colony as poisonous agents; and solutions of tobacco, lime, soot, and walnut leaves, with urine, are also stated to prove effectual in destroying them, although these latter are decidedly inferior to the two first-mentioned substances. Corrosive sublimate, indeed, appears to have a curious and even specific action upon these forms, in rendering them actually maniacal, to use a phrase which is applicable generally to the human subject alone. Under the influence even of external contact with this substance, the ants in Grenada during their ravages of last century, were observed to be singularly affected, and were seen even to attack each other with outrageous violence, an effect also corroborated of late years in Central America by Mr Belt, who saw the rabid ants collected into small balls biting one another, and seizing hold of each other in a most extraordinary fashion under the influence of the mercurial poison. The corrosive sublimate, it is stated, can be effectively used only in dry weather.

A brief description of the Termites, or white ants, may appropriately conclude the present article. These forms have already been stated to be entirely different from the familiar and true ants, and to belong to the Neuropterous insects, whereas the true ants are classed with the Hymenoptera. They resemble the true ants in living in highly organised social communities, and in being endowed with as high and as specialised instincts. But they differ from them, first, in the fact that they do not undergo a complete metamorphosis, that is, the Termite larvae and pupae resemble the perfect insect, and do not pass through the defined stages of change and development characteristic of the true ants, bees, and other insects. The young Termite, in fact, differs from the ordinary adult only in the nonpossession of eyes, and from the sexual forms in the nondevelopment of wings. The white ants inhabit the tropical regions of the world generally, but are found in the greatest abundance in tropical South America. Their nests form characteristic structures, rising sometimes to a height of 5 or 6 feet, and constructed of earthy particles worked into a mass as hard and durable as stone. Many species of Termites are known, but they resemble one another in essential structure and habits. As indicated by their popular name, they are of a whitish colour and are soft-bodied. The Termite community consists, as in the true ants, of males, females, and workers or neuters. In the true ants the latter are undeveloped females, whereas in the Termites the sex of the neuters is wholly undeterminable; and in addition the workers are invariably divided into two distinct classes: the " soldiers/ with largely-developed jaws, whose sole office is to defend the community; and the ordinary " workers," on whom devolves the entire labour of the nest. Both classes of neuters are blind; and from a close examination of the eggs, the distinctions, not only between males and females, but also between the soldiers and workers, may be easily seen. The difference in food, so powerful in the development of sex and characteristics in other insects, does not therefore operate in the case of the Termites. The entire white ant colony and species also exhibits a division into subordinate groups and classes, the recognition and characters of which are very difficult of determination. And on this, as well as upon other grounds, the organisation of the white ant community is generally to be regarded as of a higher type than that of the familiar and true ants.

Fig. 4.—White Ant (Termes bellicotus). Male.

Fig. 5.—White Ant (Termes bellicosus). Soldier.

The nest of the Termites is known as a termitarium, the essential internal arrangement of which consists of a large number and series of chambers, connected by galleries and passages. Entrance to the nest is afforded by con cealed roads and subterranean passages. A large hillock may be a compound termitarium, formed by and inhabited by different species; and certain kinds of Termites build their nests of smaller size, sometimes of the consistence of paper. Their structures may be attached to the branches of trees, or they may be entirely subterranean, or concealed under the bark or within the stems of trees. The latter species are those which destroy timber, furniture, and household objects.

Within this curious home an equally curious community is found to reside. The king and queen represent the sexual part of the community, the true neuters or workers form the greater part of the ordinary individuals, and the soldiers and winged Termites complete the list of inmates. The royal cells, tenanted by the king and queen, exist in the inmost part of the nest, and are closely guarded by a retinue of workers. The king and queen are wingless and much larger than the neuter ants. The queen Termite when within the royal cell is permanently gravid, the abdomen being immensely distended with eggs, which as they are produced, are seized upon by the workers, and conveyed to special cells prepared for their reception. The relations of the winged Termites to the other members of the nest long formed a subject of great difficulty to naturalists; but they appear to be males and females, which are ready to assume sexual relations, and to become the progenitors or kings and queens of new communities. The neuters are, accordingly, quite distinct from the sexual forms, and do not pass through any similar developmental phases, but differ from the others, even in the egg, as has been already mentioned. Occasionally a new termitarium may be found, in which a king and queen are absent, and which contains workers only. These, however, gradually prepare the nest for full completion, by bringing eggs into the cells from a neighbouring termitarium, from which the due population of the colony will be in time produced.

Fig. 6.—White Ant (Termes bellicosus). Gravid female.

The exodus or swarming of the Termites appears to resemble more nearly that of the bees, although lake that of the true ants, it is more purely reproductive in its nature, and not so much connected with the departure of fully grown forms from a hive which has become inadequate to the comfortable accommodation of all its inmates. The lame, prior to the swarming, are fed and tended by the workers, the youngest larvae receiving the greatest share of attention. The workers apparently feed the larvae by injecting a fluid from their mouths into the larval cells; and in about a year after the deposition of the eggs the larvas become fully grown, and the period of the exodus arrives. The exodus generally takes place on damp evenings, or cloudy mornings, and many extend over several days, or until such time as all the males and females have emerged from the nest. Having reached the ground, the wings of each ant are shed by a natural effect a seam or place of separation existing at the roots of the wings and after the throwing off of the wings, the surviving males and

females pair, and become the parents of new colonies. Many fall victims to the attacks of enemies, as spiders, bats, lizards, toads, and goat-suckers. The pairs that survive take up their abode in some secluded situation, as under leaves, or under a clod of earth; there the females become impregnated, and by-and-by a new hive and its population are produced. The Termites serve an important purpose, in the particular areas of the world they inhabit, in disin

tegrating, removing, and destroying decaying wood.

See Moggridge s Harvesting Ants and Trap Door Spider.s; Bates s Naturalist on tJie Amazons; Belt s Naturalist in Nicaragua, &c.

(a. w.)