CHAP. I. THE ARCHITECTURE OF ANTS.

The first objects which strike the attention in entering upon the study of the history of ants, are the art with which they form their habitations; their variety, and the manner in which they respectively answer the wants of the species who construct them. They are sometimes fabricated with earth, sometimes hewn out in the trunk of the most solid trees, or simply composed of leaves and stalks of plants collected from all quarters. They are of an astonishing size, when compared with their diminutive architects.

I hope, in the course of the present work, to bring the reader to conceive what degree of intelligence we may grant these insects, whose faculties, police, and sagacity, have been, by some authors, as much over-rated as by others not duly appreciated.

The three modes of building, of which I have just spoken, admit of numerous modifications, each species of ant being endowed with some peculiar talent. I shall mention in what they differ, after describing the general outline of their architecture, if we may express, by the same term, the simple and rude work of an insect, and an art brought to perfection by the hands of man.

1. ART OF BUILDING AMONG THE FALLOW ANTS.

The fallow ant is that ant which forms in the woods those hillocks so remarkable for their extent. It admits of easy observation, from its being above the middle size, from its operations being carried on in open day, and from the simplicity of the work in which we find it engaged. It is very common in every part of Europe, and has, therefore, occupied the attention of Linnæus, De Geer, &c., but these learned men, having noticed it under a point of view different from mine, and my plan not permitting me to mention what they say upon this head, I shall, after briefly describing these insects, commence by explaining the construction of their abode, at the same time noticing the very exact police ants of this species observe.

The working fallow ants are from three to four lines in length, and stand high upon their legs. Their head, which is larger than the corslet, is of a pale red or fallow colour at the extremity, and blackish at the top. The mouth is armed with two very strong mandibles, denticulated and hooked at the point, which they generally keep apart, and make use of, not only for attacking their enemies and tearing their prey, but in carrying burthens, and performing the labours and reparations of the ant-hill. The antennæ are black and filiform. The corslet is protuberant, raised anteriorly, compressed and truncated posteriorly, often marked with a black stain above, the rest being of a clear fallow colour. The peduncle of the abdomen is of the same colour, and bears a large scale, which is scolloped and blackish on its superior margin. The abdomen is brown or ash-coloured, slightly invested with hair, globose, composed of five rings, not counting the scale, wanting the sting, but armed with a venom-bag. The feet are brown, and the thighs, at their origin, of a reddish tint. I have described, in the Appendix, two varieties of these ants; one with a black back, another with a back of the same colour as the rest of the corslet. This difference, which scarcely affects the habitudes of these insects, separates, however, those who inhabit the woods from those who live along-side hedges, and in meadows. It is the latter only, that have the corslet stained with black and the scale on its upper margin⁠[1] brown. They both collect, near their habitation, fragments of straw, pieces of wood, little stones, leaves, and all other objects within reach, that may be of service in increasing its height, not neglecting even moths, minute shells, corn, oats, and barley, which doubtless gave rise to their ancient renown. But if this foresight, which we supposed them to possess, has not for its object to preserve them from famine during the winter, a time in which ants eat but little, especially grain, it is not the less worthy of our regard, when we consider its real purport.

That little mound which seems at the first glance only an assemblage of materials confusedly scattered, is, however, an invention as ingenious as simple to carry off the waters from the ant-hill, to defend it from the injuries of the air, and from hostile attacks, and to regulate the heat of the sun, or retain it in the interior. The mass of the different materials of which it is composed, always presents a circular dome, whose base, often covered with earth and pebbles, forms a cone, above which the wooden portion of the building is erected in the form of a sugar loaf. But this is simply the exterior covering of the ant-hill; the most considerable portion is hidden from our sight, descending to a depth of greater or less extent. Avenues constructed very carefully of an irregular funnel shape conduct from the roof to the interior. Their number depends upon the population of the nest and its extent. The entrance to the nest is more or less considerable. We sometimes find a spacious aperture at the top, but more frequently, several apertures of nearly equal size, around which are many narrow passages, symmetrically and circularly disposed, which extend even to the base of their habitation.

These several apertures were necessary to give a free egress to the vast multitude of labourers of which their colony is composed. Not only do they work continually on the outside of their nest, but differing very essentially from other species who willingly remain in the interior sheltered from the sun, they prefer living in the open air, and do not hesitate carrying on, even in our presence, the greater part of their operations.

In the habitations of the yellow ant, the dark ash-coloured ant, the sanguine ant, the brown ant, &c. we never observe the entrances of sufficient width to allow their enemies easy access, or permit the introduction of the rain. They are covered with a dome of earth, closed on all sides, and have no outlet but near the base, which is by a long and tortuous passage that winds to the distance of several feet in the grass. The diminutive size of these apertures, at all times diligently guarded within, prevents the entrance of any insects or reptiles that may happen to arrive there.

The fallow ants, collected in crowds during the day on their nest, have no fear of being disquieted in the interior, but when, in the evening, they retire to their quarters, no longer perceiving what passes without, how are they screened from the accidents with which they are menaced? or how happens it that the rain does not penetrate their abode, open as it is on every side to its introduction? These questions, simple as they are, do not appear to have engaged the attention of naturalists. Have they not then foreseen the dangers to which these insects would have been exposed, if that wisdom which regulates the universe had not provided for their safety? Struck with these reflections, when I first noticed the fallow ants, I directed my entire attention to this subject, and soon acquired the information I wanted. I remarked that their habitations changed in appearance hourly, and that the diameter of those spacious avenues, where so many ants could freely pass each other during the day, was, as night approached, gradually lessened. The aperture at length totally disappeared, the dome was closed on all sides, and the ants retired to the bottom of their nest.

In further noticing the apertures of these ant-hills, I fully ascertained the nature of the labour of its inhabitants, of which I could not before even guess the purport; for the surface of the nest presented such a constant scene of agitation, and so many insects were occupied in carrying materials in every direction, that the movement offered no other image than that of confusion.

I saw then clearly that they were engaged in stopping up their passages; and for this purpose, they at first brought forward little pieces of wood, which they deposited near the entrance of those avenues they wished to close, they placed them above the aperture, and even sunk them in the stubble; they then went to seek other ligneous fragments which they disposed above the first, but in a different direction, and appeared to choose fragments of less size in proportion as the work advanced. They at length brought in a number of dried leaves, and other materials of an enlarged form, with which they covered the roof. Is not this in miniature the art of our builders when they form the covering of any building? Nature seems every where to have anticipated the inventions of which we boast. This is doubtless one of the most simple.

Our little insects, now in safety in their nest, retire gradually to the interior before the last passages are closed, one or two only remain without, or concealed behind the doors on guard, whilst the rest either take their repose, or engage in different occupations in the most perfect security.

I was impatient to know what took place in the morning upon these ant-hills, and therefore visited them at an early hour. I found them in the same state in which I had left them the preceding evening. A few ants were wandering about on the surface of the nest, some others issued from time to time from under the margin of the little roofs formed at the entrance of the galleries: others afterwards came forth who began removing the wooden bars that blockaded the entrance, in which they readily succeeded. This labour occupied them several hours. The passages were at length free, and the materials with which they had been closed scattered here and there over the ant-hill.

Every day, morning and evening, during the fine weather, I was a witness to similar proceedings. On days of rain, the doors of all the ant-hills remain closed. When the sky is cloudy in the morning, or rain is indicated, the ants, who seem to be aware of it, open but in part their several avenues, and immediately close them when the rain commences. It would appear from this they are not insensible of the motive for which they form these temporary closures.

To have an idea how the straw or stubble roof is formed, let us take a view of the ant-hill at its origin, when it is simply a cavity in the earth. Some of its future inhabitants are seen wandering about in search of materials fit for the exterior work, with which, though rather irregularly, they cover up the entrance; whilst others are employed in mixing the earth, thrown up in hollowing the interior, with fragments of wood and leaves, which are every moment brought in by their fellow-assistants; and this gives a certain consistence to the edifice, which increases in size daily. Our little architects leave here and there cavities where they intend constructing the galleries which are to lead to the exterior, and as they remove in the morning the barriers placed at the entrance of their nest the preceding evening, the passages are kept entire during the whole time of its construction. We soon observe it to become convex; but we should be greatly deceived did we consider it solid. This roof is destined to include many apartments or stories. Having observed the motions of these little masons through a pane of glass which I adjusted against one of their habitations, I am enabled to speak with some degree of certainty upon the manner in which they are constructed.

It is by excavating or mining the under portion of their edifice that they form their spacious halls, low indeed and of heavy construction, yet sufficiently convenient for the use to which they are appropriated, that of receiving at certain hours of the day the larvæ and pupæ.⁠[2]⁠

These halls have a free communication by galleries made in the same manner. If the materials of which the ant-hill is composed were only interlaced, they would fall into a confused heap every time the ants attempted to bring them into regular order. This, however, is obviated by their tempering the earth with rain-water, which afterwards hardening in the sun, so completely and effectually binds together the several substances as to permit the removal of certain fragments from the ant-hill, without any injury to the rest: it, moreover, strongly opposes the introduction of the rain. I never found, even after long and violent rains, the interior of the nest wetted to more than a quarter of an inch from the surface, provided it had not been previously out of repair, or deserted by its inhabitants.

The ants are extremely well sheltered in their chambers, the largest of which is placed nearly in the centre of the building; it is much loftier than the rest, and traversed only by the beams that support the ceiling: it is in this spot that all the galleries terminate, and this forms, for the most part, their usual residence.

As to the under-ground portion, it can only be seen when the ant-hill is placed against a declivity; all the interior may be then readily brought in view, by simply raising up the straw roof. The subterranean residence consists of a range of apartments, excavated in the earth, taking an horizontal direction.

That part of the architecture of fallow ants, which equally obtains with the mason-ants, and of which I shall soon have occasion to speak, I shall not now stop to describe, but pass on immediately to the labours of the latter, which will be found to merit our attention.

2. ARCHITECTURE OF THE MASON-ANTS.

I term those mason-ants, whose nests, on the exterior, have the appearance of hillocks of earth, without admixture of other materials, whilst in the interior they present a series of labyrinths, lodges, vaults, and galleries, constructed with great art.

There are several species of mason-ants. The earth, of which their nest is composed, is more or less compact. That which ants of a certain size, such as the ash-coloured and mining ants employ, appears to be less selected, and forms a less fine paste, than that of which the brown, microscopic, and yellow ants form their abode. It is, however, sufficiently adapted to their use, and to the nature of the edifice they intend erecting.

To form a correct judgment of the interior arrangement or distribution of an ant-hill, it is necessary to select such as have not been accidentally spoiled, or whose form has not been too much altered by local circumstances; a slight attention will then suffice to show, that the habitation of the different species are not all constructed after the same system. Thus, the hillock raised by the ash-coloured ants will always present thick walls, fabricated with coarse earth, well-marked stories, and large chambers, with vaulted ceilings, resting upon a solid base. We never observe roads or galleries, properly so called, but large passages, of an oval form, and all around considerable cavities and extensive embankments of earth. We further notice, that the little architects observe a certain proportion between the large arched ceilings and the pillars that are to support them.

The brown, one of the smallest of the ants, is particularly remarkable for the extreme finish of its work. Its body is of a reddish shining brown, its head a little deeper, and the antennæ and feet a little lighter in colour. The abdomen is of an obscure brown, the scale narrow, of a square form, and slightly scolloped. The body is one line and two-fifths in length.⁠[3]⁠

This ant, one of the most industrious of its tribe, forms its nest of stories, four or five lines in height. The partitions are not more than half a line in thickness, and the substance of which they are composed is so finely grained, that the inner walls present one smooth, unbroken surface. These stories are not horizontal: they follow the slope of the ant-hill, and lie one upon the other to the ground-floor, which communicates with the subterranean lodges. They are not always, however, arranged with the same regularity, for these ants do not follow an invariable plan; it appears, on the contrary, that nature has allowed them a certain latitude in this respect, and that they can, according to circumstances, modify them to their wish:—but, however fantastical their habitations may appear, we always observe they have been formed by concentrical stories. On examining each story separately, we observe a number of cavities or halls, lodges of narrower dimensions, and long galleries, which serve for general communication. The arched ceilings covering the most spacious places are supported, either by little columns, slender walls, or by regular buttresses. We also notice chambers that have but one entrance, communicating with the lower story, and large open spaces, serving as a kind of carrefour, or cross-road, in which all the streets terminate. Such is the manner in which the habitations of these ants are constructed. Upon opening them, we commonly find the apartments, as well as the large open spaces, filled with adult ants, and always observe their pupæ collected in the apartments, more or less near the surface. This, however, seems regulated by the hour of the day, and the temperature; for in this respect these ants are endowed with great sensibility, and know the degree of heat best adapted for their young. The ant-hill contains sometimes more than twenty stories in its upper portion, and at least as many under the surface of the ground. By this arrangement the ants are enabled, with the greatest facility, to regulate the heat. When a too burning sun overheats their upper apartments, they withdraw with their little ones to the bottom of the ant-hill. The ground-floor becoming, in its turn, uninhabitable, during the rainy season, the ants of this species transport what most interests them to the higher stories, and it is there we find them more usually assembled with their pupæ and eggs, when the subterranean apartments are submerged.⁠[4] Having ascertained the internal arrangement of their habitations, it was still an object of discovery, how ants, working with a substance so hard, could trace out and finish works so extremely delicate, with the assistance only of their teeth, how they could soften the earth, for the purpose of mining, kneading, and building with it, and what cement they employed to unite its several particles into one mass. Did it depend upon a sort of mucilage or resin, or some other liquid furnished by the ants themselves, similar to what the mason-bee employs in building the nest to which it gives so much solidity? I ought, perhaps, to have analysed the earth of which these ant-hills are composed, but I was fearful of engaging in difficulties that did not come within my immediate province, and therefore kept to the slow but sure method of observation, by which I hoped to obtain the same result.

I hastened, then, to observe one of these ant-hills, until I should perceive some change in its form.

The inhabitants of that I had selected kept within during the day, or only went out by the subterranean galleries, which opened at some feet distance in the meadow. There were, however, two or three small openings on the surface of the nest, but I saw none of the labourers pass out this way, on account of their being too much exposed to the sun, which these insects greatly dread.

This ant-hill, which had a round form, rose in the grass at the border of a path, and had sustained no injury. I soon perceived that the freshness of the air and the dew invited the ants to walk over the surface of their nest; they began making new apertures; several ants might be seen arriving at the same time, thrusting their head from the entrances, moving about their antennæ, and at length adventuring forth to visit the environs.

This brought to my recollection a singular opinion of the ancients. They believed that ants were occupied in their architectural labours during the night, when the moon was at its full.⁠[5] This idea was not, perhaps, without some foundation, and although the moon had doubtless no kind of influence on their conduct, yet I perceived something true in the observation.

Having then noticed the movements of these insects during the night, I found they were almost always abroad and engaged about the dome of their habitation after sun-set. This was directly the reverse of what I had observed in the conduct of the fallow ants, who only go out during the day, and close their doors in the evening. The contrast was still more remarkable than I had previously supposed, for upon visiting the brown ants, some days after, during a gentle rain, I saw all their architectural talents in full play.

As soon as the rain commenced, they left, in great numbers, their subterranean residence, re-entered it almost immediately, and then returned, bearing between their teeth pellets of earth, which they deposited on the roof of their nest. I could not, at first, conceive, what this was meant for, but at length I saw little walls start up on all sides with spaces left between them. In several places, columns, ranged at regular distances, announced halls, lodges, and passages, which the ants proposed establishing; in one word, it was the ebauche of a new story.

I watched with a considerable degree of interest, the most trifling movements of my Masons, and found they did not work, after the manner of wasps and humble-bees, when occupied in constructing a covering to their nest. The latter sit as it were a-stride (se mettent pour ainsi dire à cheval) the border or margin of this covering, and take it between their teeth to model and attenuate it according to their wish. The wax of which it is composed, and the papier which the wasp employs, moistened by some kind of glue, are admirably adapted for this purpose; but the earth (often possessing but little tenacity) of which the ants make use, must be worked up after some other manner.

Each ant, then, carried between its teeth the pellet of earth it had formed, by scraping with the end of its mandibles, the bottom of its abode, which I have often witnessed in open day. This little mass of earth, being composed of particles but just united, could be readily moulded as the ants wished: thus, when they had applied it to the spot where it was to rest, they divided, and pressed against it with their teeth, so as to fill up the little inequalities of their wall. The antennæ followed all their movements, passing over each particle of earth as soon as it was placed in its proper position. The whole was then rendered more compact, by pressing it lightly with the fore-feet. This work went on remarkably quick. After having traced out the plan of their masonry, in laying here and there foundations for the pillars and the partitions they were about to erect, they gave them more relief by adding fresh materials. It often happened that two little walls, which were to form a gallery, were raised opposite, and at a slight distance from each other. When they had attained the height of four or five lines, the ants busied themselves in covering in the space left between them by a vaulted ceiling.

Quitting, then, their labours in the upper part of the building, as if they judged all their partitions of sufficient elevation, they affixed to the interior and upper part of each wall, fragments of moistened earth, in an almost horizontal direction, and in such a way, as to form a ledge which, by extension, would be made to join that coming from the opposite wall. These ledges were about half a line in thickness; and the breadth of the galleries was, for the most part, about a quarter of an inch. Here several vertical partitions were seen to form the scaffolding of a lodge, which communicated with several corridors, by apertures formed in the masonry; there, a regularly formed hall, the vaulted ceiling of which was sustained by numerous pillars; further off might be recognised the rudiments of one of those carrefours of which we have before spoken, and in which several avenues terminate. These parts of the Ant-hill were the most spacious; the ants, however, did not appear embarrassed in constructing the ceiling to cover them in, although they were often more than two inches in breadth.

In the upper part of the angles formed by the different walls, they laid the first foundations of this ceiling, and from the top of each pillar, as from so many centres, a layer of earth, horizontal and slightly convex, was carried forward to meet the several portions coming from different points of the large public thoroughfare.

This busy crowd of Masons, arriving from all parts with the piece of mortar they wish to add to the building, the order they observe in their operations, the harmony which prevails, and the eagerness with which they avail themselves of the rain to increase the height of their abode, present to the contemplative observer a scene of considerable interest.

I sometimes, however, laboured under an apprehension that the building could not possibly resist its own weight, and that such extensive ceilings, sustained only by a few pillars, would fall into ruin from the rain which continually fell upon them;—but I was quickly convinced of their stability, from observing that the earth, brought by these insects, adhered at all points, on the slightest contact; and that the rain, so far from lessening the cohesion of its particles, appeared even to increase it. Thus, instead of injuring the building, it even contributed to render it still more secure.

These parcels of moistened earth, which are only held together by juxtaposition, require a fall of rain to cement them more closely, and thus varnish over, as it were, those places where the walls and galleries remain uncovered. All inequalities in the masonry then disappear. The upper part of these stories, formed of several pieces brought together, presents but one single layer of compact earth. They require for their complete consolidation nothing but the heat of the sun. It sometimes, however, happens that a violent rain will destroy the apartments, especially should they be but slightly arched; but under these circumstances the ants reconstruct them with wonderful patience.

These different labours were carried on at the same time, and were so closely followed up in the different quarters, that the Ant-hill received an additional story in the course of seven or eight hours. All the vaulted ceilings, being formed upon a regular plan, and at equal distances from one wall to the other, constituted, when finished, but one single roof. Scarcely had the ants finished this story than they began constructing another; but they had not time to finish it: the rain ceasing before the ceiling was fully completed. They still, however, continued their work for a few hours, taking advantage of the humidity of the earth; but a keen north wind soon sprung up, and hastily dried the collected fragments, which, no longer possessing the same adherence, readily fell into powder. The ants, finding their efforts ineffectual, were at length discouraged, and abandoned their employment; but what was my astonishment, when I saw them destroy all the apartments that were yet uncovered, scattering here and there over the last story, the materials of which they had been composed! These facts incontestably prove, that they employ neither gum, nor any kind of cement to bind together the several substances of their nest, but in place of this avail themselves of the rain, to work or knead the earth, leaving the sun and wind to dry and consolidate it.⁠[6] In the simplicity of these means, I recognised the hand of Nature: however, I still thought it necessary to make an experiment to be convinced of the correctness of these results. A few days after, I endeavoured to excite them to recommence their labours by an artificial shower. With this view, I took a very strong brush which I plunged in water, and passing my hand backwards and forwards over the hairs, produced upon the surface of the Ant-hill a very fine dew. The ants perceiving from the interior of their dwelling, the humidity of the roof, came out and passed rapidly over the surface; the sprinkling was continued; the Masons were deceived. They went to the bottom of the Nest to provide themselves with little masses of Earth, which they afterwards brought and deposited on the roof; they then constructed walls and chambers; in a word, a complete story was erected in the course of a few hours. This experiment I frequently repeated, and always with the same success. It is in the Spring more particularly, that the Mason Ants avail themselves of the rain when they wish to enlarge the boundaries of their nest. Night even does not arrest their progress. I have often noticed in the morning stories that had been completely erected during the night.

The ants, not content with giving additional elevation to their abode, hollow out, in the earth, apartments still more spacious; the materials thus obtained, are, as before stated, employed in the exterior construction. The art of these insects, therefore, consists in their executing, at the same time, two contrary operations, the one of mining, the other of building, making the former subservient to the latter; and what is still as singular, the same talent is manifested in these excavations, as in that portion of the building above ground. The humidity which penetrates to the bottom of their nest, is doubtless of great assistance to them in these labours.⁠[7]⁠

3. ARCHITECTURE OF THE DARK ASH-COLOURED ANTS.

These Ants, which are fully described in the Appendix, are distinguished, according to Latreille, by their having the body, head, and abdomen, of a shining dark ash-colour, the base of the antennæ and the feet reddish, the scale large and nearly triangular, and three small ocelli or simple eyes.

The Ash-coloured Ants build in a manner very different from the Brown Ants. We have already seen from the description of their dwelling, that, in comparison to the latter, it is exceedingly simple and heavy in its construction. This simplicity, however, was better adapted to my object,—that of examining, if possible, how many ants could concur in the execution of the same design, and how far they appeared to understand each other in the general progress of their labour;—that of discovering also, if they acted in concert, or independently of each other; of their own accord, or from some general impulse. I do not flatter myself that I have solved these important questions, but the facts I am about to adduce, will, at least, serve to elucidate this subject.

When the Ash-coloured Ants seem desirous to give greater elevation to their dwelling, they commence, by placing over the roof a thick layer of earth, which they bring from the interior. It is here they trace en creux et en relief, the plan of a new story; they, at first, form here and there little dykes more or less close to each other, and of a breadth proportioned to the use for which they are designed: they give them nearly equal depth, for the most part equalling their breadth: the masses of earth left between them, serve afterwards, for the foundation of the inner walls. Having removed all the useless earth from the bottom of each chamber, and reduced to their proper thickness the foundation of the walls, the architects have nothing more to do, than to increase the height of their building, and cover over with a ceiling the several apartments.

After witnessing the manner in which these ant-hills are constructed, I was aware that the best and only mode of attaining a correct knowledge of their organization, was that of following individually the conduct of the Labourers engaged in erecting them. My journals are filled with observations of this nature. I extract a few that seem to possess some interest. I shall at present describe the operations of a single ant that I observed sufficiently long to satisfy my curiosity.

One rainy day, I observed a Labourer digging the ground near the aperture which gave entrance to the ant-hill. It placed in a heap the several fragments it had scraped up, and formed them into small pellets, which it deposited here and there upon the nest. It returned constantly to the same place, and appeared to have a marked design, for it laboured with ardour and perseverance. I remarked a slight furrow, excavated in the ground in a straight line, representing the plan of a path or gallery. The Labourer, the whole of whose movements fell under my immediate observation, gave it greater depth and breadth, and cleared out its borders; and I saw, at length—in which I could not be deceived—that it had the intention of establishing an avenue which was to lead from one of the stories to the under-ground chambers. This path, which was about two or three inches in length, and formed by a single ant, was opened above, and bordered on each side by a buttress of earth: its concavity en forme de gouttiere was of the most perfect regularity; for the architect had not left an atom too much. The work of this ant was so well followed and understood, that I could almost to a certainty guess its next proceeding, and the very fragment it was about to remove. At the side of the opening where this path terminated, was a second opening to which it was necessary to arrive by some road. The same ant engaged in and executed alone this undertaking. It furrowed out and opened another path, parallel to the first, leaving between each a little wall of three or four lines in height.

Those ants who lay the foundation of a wall, a chamber, or gallery, from working separately, occasion now and then a want of coincidence in the parts of the same or different objects. Such examples are of no unfrequent occurrence, but they by no means embarrass them. What follows proves that the workman, on discovering his error, knew how to rectify it.

A wall had been erected with the view of sustaining a vaulted ceiling, still incomplete, that had been projected from the wall of the opposite chamber. The workman who began constructing it, had given it too little elevation to meet the opposite partition upon which it was to rest. Had it been continued on the original plan, it must infallibly have met the wall at about one-half of its height, and this it was necessary to avoid. This state of things very forcibly claimed my attention; when one of the ants, arriving at the place, and visiting the works, appeared to be struck by the difficulty which presented itself; but this it as soon obviated, by taking down the ceiling and raising the wall upon which it reposed. It then, in my presence, constructed a new ceiling with the fragments of the former one.

When the ants commence any undertaking, one would suppose that they worked after some preconceived idea, which indeed would seem verified by the execution. Thus, should any ant discover upon the nest, two stalks of plants, which lie cross-ways, a disposition favourable to the construction of a lodge; or some little beams that may be useful in forming its angles and sides, it examines the several parts with attention, then distributes with much sagacity and address parcels of earth, in the spaces, and along the stems, taking from every quarter materials adapted to its object, sometimes, not caring to destroy the work that others had commenced; so much are its motions regulated by the idea it has conceived, and upon which it acts, with little attention to all else around it. It goes and returns, until the plan is sufficiently understood by its companions.

In another part of the same ant-hill, several fragments of straw seemed expressly placed to form the roof of a large house; a workman took advantage of this disposition: these fragments lying horizontally, at half an inch distance from the ground, formed, in crossing each other, an oblong parallelogram. The industrious insect commenced, by placing earth in the several angles of this carpentering work, and all along the little beams of which it was composed. The same workman afterwards placed several rows of the same materials against each other, when the roof became very distinct. On perceiving the possibility of profiting by another plant, to support a vertical wall, it began laying the foundations of it; other ants having by this time arrived, finished in common what this had commenced.⁠[8]⁠

From these observations, and a thousand similar, I am convinced that each ant acts independently of its companions. The first who conceives a plan of easy execution, immediately gives the sketch of it; others have only to continue what this has begun, judging, from an inspection of the first labours, in what they ought to engage. They can all lay down plans, and continue to polish or retouch their work as occasion requires. The water furnishes the cement they require, and the sun and air harden the materials of which their edifice is composed. They have no other chisel than their teeth, no other compass than their antennæ, and no other trowel than their fore-feet, of which they make use in an admirable manner, to affix and consolidate the moistened earth.

These, then, are the material and mechanical means which they employ in their building. In following an instinct purely mechanical, they might execute with precision, a geometrical and invariable plan, construct walls of equal length and breadth, vaulted ceilings, whose curve would only require a servile obeissance, and we should have been but moderately surprised by their industry: but to form these irregular domes, composed of so many stories; to distribute in a convenient, yet varied manner, the apartments they include, and to seize the most favourable time for their labours, but especially to vary them according to circumstances; to profit by the points d’appui that may present themselves; and to judge of the advantage of such and such operations, is it not necessary they should be endowed with faculties closely approaching intelligence, and that, far from considering them as automatons, Nature allows them to perceive the intention of those labours in which they have been engaged?⁠[9]⁠

I could readily bring forward numberless examples of the industry of ants, in still mentioning after what manner several other species construct their abode; but, not to abuse or weary the patience of my readers, I shall not enter into a detail of the labours of the Field Ants, who build little chambers, one above the other, along the stems of plants, and who can, in time of need, connect grains of sand, by juxta-position alone, or by the admixture of a little moistened earth; nor of those of the Sanguine Ant, who are enabled to form from earth, dry leaves, and other materials, a compact tissue, difficult to break, and impenetrable to water; nor of those covered galleries, which the Brown Ants construct with earth, conducting from their nest to the feet of trees, and sometimes even to the origin of the branches, for the purpose of arriving with greater security at the places where they find their food.

4. ARCHITECTURE OF ANTS THAT FORM THEIR HABITATION IN TIMBER.

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Is it not a matter of astonishment, that Nature should have given to insects of the same genus, manners so varied, and an industry so widely different? Ants furnish us with one of the most striking examples of this kind. We have just completed a sketch of the several species of Mason-ants; each building in a different manner, and offering some striking peculiarities in the style and mode of their architecture. That of the Fallow-ants is founded upon different principles, and the industry of those who excavate their dwelling in wood, has no point of resemblance with that of the species of which we have lately treated. This tribe of ants includes several species; and we still observe in their architectural labours very sensible shades of difference: all these insects enter into the first of the nine divisions into which Latreille has distributed ants, it includes the Brown, the Ash-coloured, the Fallow, the Mining, the Sanguine, the Fuliginous, and the Yellow Ant, &c. These ants possess the same exterior organs, a similarity of the means employed in constructing their dwellings, and resemblances in figure, which have occasioned them to be placed under the same division; their instinct, however, places them at a considerable distance from each other, plainly showing that we cannot always form a correct judgment of the manners and customs of insects from analogy.

The labours of those ants that inhabit trees, or what we may term Timber Ants, are less open to general observation than those already described, and have, in consequence, received but little attention from naturalists.

The ant holding the first rank in this division, is, the Fuliginous, so called on account of its colour. It is of a shining black, and is two lines in length; its republics, composed of a great number of individuals, are less common than those of which we have hitherto spoken.

Let us figure to ourselves the interior of a tree entirely sculptured or hollowed out, consisting of numberless stories, more or less horizontal, whose floors and ceilings are at five or six lines’ distance from each other, and as thin as a card, supported at one time by vertical partitions, forming an infinity of chambers; at another time, by a series of small slender columns, allowing us to observe between them the extent of an almost entire story; the whole, composed of a blackish, and as it were smoked wood; and we shall have a just idea of the cities of these ants.

The greater number of the vertical partitions, which divide each story into compartments, are parallel; they follow the course of the ligneous layers, and are always concentrical, which gives to their work some degree of regularity. The floors, generally speaking, are horizontal. The little columns are from one to two lines in thickness, more or less round, of a height equal to that of the story they support, larger above and below than in the middle, a little flattened at the capital and base, and ranged in regular lines, since they have been worked out in the parallel partitions. What numerous apartments! What a series of lodges, halls and corridors do these insects not form by their own unsupported industry; and what labour in so great an undertaking does it not cost them!

The wood, in which ants of this species excavate these labyrinths, takes a blackish hue:—does this arise from the extravasated fluids of the tree entering into combination with the external air, or from the emanation of the ants themselves, the odour of which may perhaps have some influence; or do the layers of wood, exposed by these insects, undergo any decomposition from combining with the formic acid? I cannot decide this question; but I rest well assured, that the wood hewn by these insects, is always blackish externally, and even takes the same colour internally, provided it be very thin, preserving only its natural colour when it has any degree of thickness. It appears that the oak, willow, and other trees in which these ants establish themselves, equally take these colours. I have often observed several other species of ants lodged in the interior of trees, but the wood never presented the same appearance. I have also often noticed at the foot of those which were inhabited by Fuliginous Ants, a very abundant and blackish liquid:—to what must this be attributed? The vegetation of these trees does not appear in the slightest degree affected by the labours of these insects.

It would be a highly interesting sight, could we observe ants occupied in carving the wood in which they fix their residence, we might then learn the origin of the black tint with which it is imbued; but the labourers of this species working always in the interior of trees, and desirous of being screened from observation, precludes every hope, on our part, of following them in their several occupations. I tried every expedient I could devise to surmount this difficulty; I endeavoured to accustom these ants to live and work under my inspection, but all my efforts were unsuccessful; they even abandoned the most considerable portion of their nest to seek some new asylum, and spurned the honey and sugar I offered them for nourishment. I was now, of necessity, limited to the inspection alone of these edifices; but by decomposing some of the fragments with care, I hoped to acquire some knowledge of their organization. Here, we perceive horizontal galleries, hidden in great part by their walls, which follow the circular direction of the ligneous layers; there, parallel galleries, separated by extremely thin partitions, having no communication except by a few oval apertures. Such is the nature of these works, remarkable for their delicacy and lightness.

In other fragments we notice avenues, opened laterally, including portions of walls and transverse partitions, erected here and there, within the galleries, so as to form separate chambers. When the work is further advanced, we always observe round holes, encased, as it were, between two pillars, cut out in the same wall. These holes in course of time become square, and the pillars, originally arched at both ends, are worked into regular columns by the chisel of our sculptors. This, then, is the second specimen of their art. This portion of the edifice will probably remain in this state.

But here are fragments differently wrought, in which these same partitions, pierced now in every part, and hewn skilfully, are transformed into colonnades, which sustain the upper stories, and leave a free communication throughout their whole extent. We can readily conceive how parallel galleries hollowed out upon the same plan, and the sides taken down, leaving only from space to space what is necessary to sustain their ceilings, may form an entire story; but as each has been pierced separately, the flooring cannot be very level: this, however, the ants turn to their advantage, since these furrows are better adapted to retain the larvæ that may be placed there.

The stories constructed in the great roots offer greater irregularity than those in the very body of the tree, arising, either from the hardness and interlacing of the fibres, which renders the labour more difficult, and obliges the labourers to depart from their accustomed manner, or from their not observing in the extremities of their edifice the same arrangement as in the centre: whatever it be, we still find horizontal stories, and numerous partitions. If the work be less regular, it becomes more delicate; for the ants, profiting by the hardness and solidity of the material, give to their building an extreme degree of lightness. I have seen fragments of from eight to ten inches in length and of equal height, formed of wood as thin as paper, containing a number of apartments, and presenting the most singular appearance. At the entrance of these apartments, worked out with so much care, are very considerable openings; but, in place of chambers, and extensive galleries, the layers of the wood are hewn in arcades, allowing the ants a free passage in every direction. These may be regarded as the gates or vestibules conducting to the several lodges.

Fig. 3. and 4., Pl. I., give but a very imperfect idea of the labours of these insects. The first represents a fragment taken from the trunk of an oak inhabited by Fuliginous Ants; the second, a small portion of their nest, taken from the roots of the same tree. To judge properly of these fragments, we should place them in every position, we shall then better observe their singular organization.

The Red Ant, a little larger than the preceding, forms a lodging in trees, very analagous to the above, but upon a much smaller scale. Their dwelling consists of stories more or less developed; some divided into little chambers or lodges, the walls of which are remarkably thin; others sustained by an infinity of little columns, resembling, in size and colour, those of which we have already spoken. The wood, however, is not blackened, as is the case with that excavated by the Fuliginous Ants, but retains its original colour. It is commonly less hard, and of the consistence of cork.

But what is most remarkable in the history of Red Ants is, that they are not only carvers, but even skilful masons. They more frequently fix their residence in the earth. This is not, however, the only species that can, in time of need, display more than one talent in this department. We are about to notice two kinds of ants which also enjoy this privilege, the Ethiopian and the Yellow Ant. They have also an art peculiar to them, of which I have not yet treated, and which must be regarded as belonging to the architecture of ants.

5. ARCHITECTURE OF THOSE ANTS THAT FORM THEIR RESIDENCE OF SAW-DUST, DECAYED TIMBER, &C.

The Ethiopian Ants, thus named, on account of their jet-black colour, hollow out extensive lodges and long galleries in the oldest trees; but if their works are proportioned to their size, which is greater than that of other ants, they scarcely represent the infancy of the art by the manner in which they are executed. What is most remarkable in their industry is, the use they make of the wood fallen into powder at the foot of the tree they inhabit, to stop up every chink in the flooring of their houses, to close useless passages, and to make compartments in those labyrinths which are too spacious.

The Yellow, one of the mason ants, shows great skill in the employment of this substance, when it establishes its residence in a hollow tree; it constructs entire stories with decayed wood, selecting the finest particles, which, on being mixed up at the bottom of the tree with a little earth and spider’s web, forms a mass of the consistency of papier mâché. This industry recalls to mind that of wasps, as the labours of the Mason and Timber Ants bring to our recollection those of the Mason and Timber Bees.

The class of hymenopterous insects, the richest of all in varied industry, in original manners and customs, in curious instinct, offers, continually, similarities and contrasts; connections between genera the farthest removed, and striking differences between species the most approximate. The moral condition of these insects does not appear to follow their physical condition; a truth of some importance to animal physiology.