The Industries of Animals

by Frédéric Houssay

The centre of the ground-floor, therefore, is occupied by the royal apartment; around this, and communicating with it by means of numerous entrances, are a number of cells used by the attendants on the queen (s). These little chambers are surrounded by a labyrinth of passages. The central room and its dependencies constitute a solid mass, around which other chambers are grouped. The whole space between it and the general wall is filled by vast storehouses, divided into many very spacious compartments. Within them are piled up the provisions which the Termites harvest every day; they consist especially of gums and the juices of plants, dried and pulverised so as to form a fine powder. Access to this property is given by means of large corridors which cross one another, and conduct to the outside through the horizontal galleries traversing the wall.

Above the whole of this ground-floor rests a thick vault of clay, which forms a strong floor for the first storey (B). This is composed of only a single room; it is put to no use, unless to isolate and support the apartments of the second floor, in the arrangement of which great care is exercised. There are no partitions on this floor, nothing but massive columns of clay to support the ceiling. These columns are more than a metre in height. It is a gigantic cathedral in which the lilliputian architects have displayed considerable art. By means of this immense empty chamber a huge reservoir of air is placed in the very centre of the construction; through the galleries in the external wall it is sufficiently renewed for the purposes of respiration without too great a change in temperature.

The second storey rests on the first. To this the eggs are brought, and here the larvæ go through their evolution. Partitions of clay divide the space into a few large halls (a); these are again subdivided, this time not by earth, which is employed throughout the rest of the building, but by materials of a more delicate kind, which are, moreover, very bad conductors of heat (b). It is a question, in fact, of maintaining these little chambers at an almost constant temperature, favourable for the development of the eggs. The substances utilised for this purpose are fragments of wood and of gum. The Termites glue them together and thus form the walls of these important cells.

The arrangement of the top storey (D) is also disposed with a view of protecting the young who are the future of the city. It constitutes the attic, situated just beneath the cupola, and contains absolutely nothing; it simply serves to interpose beneath the summit of the edifice and the storey below a layer of air, which is a bad conductor of heat. The chamber devoted to the young is thus placed between two gaseous layers, a precaution which, combined with the choice of material, places it in the very best conditions for protection against the alternation of cold at night and torrid heat during the day.

It is difficult to know which to admire most — the audacity and vastness of the labour undertaken by these insects, or the ingenious foresight by which they ensure to their delicate larvæ a comfortable youth. There can be no doubt that these animals show themselves very superior to Man, taking into consideration his enormous size compared to theirs, in the art of building. Pillars, cupolas, vaults — nothing is too difficult or too complicated for these small and patient labourers.[103]

The Ants of our own lands do not yield to the Termites in this industry, and their dwellings are models of architecture. As they have been more carefully studied we know more exactly how they work, and the considerable sum of intelligence and initiative which they reveal in the accomplishment of their task. At the foot of hedges, on the outskirts of woods, they raise their frail monuments. The species are not equally skilful, and such differences as we have found in other industries may also be found here. In a general manner it was soon found that Ants do not, like Bees, obey a rigid instinct which ordains the line of conduct under every circumstance, and impels each individual to act so that his efforts are naturally combined and harmonised with those of his neighbours in the workshop. One soon perceives when observing an ant-hill that any individual insect follows, when working, a personal idea which it has conceived, and which it realises without troubling itself about the others. Often these latter are executing a quite contradictory plan. It is rather an anarchistic republic. Happily Ants are not obstinate, and when they see the idea of one of them disengaging itself from the labour commenced, they are content to abandon their own less satisfactory idea and to collaborate in the other’s work. They are able, for the rest, to concert plans; the movements of their antennæ are a very complicated language containing many expressions, and the worker who desires the acceptance of his own point of view is not sparing in their use.[104] It sometimes happens that his efforts are vain, and that his companions manœuvre to thwart his schemes. In the presence of such resistance those who are determined to obtain the adoption of their own plans destroy the labours of their opponents; fierce struggles ensue, and here it is the strongest who becomes the architect-general.

The Formica fusca constructs its nest of plastered earth. The different superimposed storeys have been added one by one to the upper part of the old dwelling when the latter became too small for the growing colony. In opening an ant-hill, they are found to be quite distinct from each other; each is divided by a large number of partitions into vaulted compartments. In the larger ones pillars of earth support the ceiling. The rooms communicate with one another by means of bull’s-eye passages formed in the separating walls. The whole is small, proportioned to the size of the works, but excellently arranged.

When, in the council of the republic, it has been resolved to raise a common habitation, the workers operate in a singular manner. All the ants scatter themselves abroad, and with extreme activity take fragments of earth between their mandibles and place them on the summit of the dwelling. After some time the result of this microscopical work appears. The ancient roof, strengthened by all this material, becomes a thick terrace which the insects first cover very evenly. The earth, having been brought in grain by grain, is soft and easy to dig. The construction of the new storey begins at first by the hollowing out of a number of trenches. The ants scrape away in places the terrace which they have just made. They thus diminish the thickness of the layer at the spots where rooms, corridors, etc., are to be formed, and with the material thus obtained they form walls, partitions, and pillars. Soon the entire plan of the new storey may be perceived. It differs essentially from that which Man would adopt; in the latter case the walls would be shown by the hollowing out of the foundations; the work of these Hymenoptera, on the contrary, shows them in relief. These first arrangements made, the six-footed architects have only to complete their constructions by new deposits from without. Gradually the storey reaches a sufficient height. It remains to cover it, and this is not the easiest part of the business. The ceiling is formed of vaults going from one wall to another, or from a wall to a column. When one of these vaults is to be small, some millimetres at the most, the Formica fusca constructs it with the help of two ledges, which are made facing each other on the tops of two partitions. These prominences, formed of materials glued together by saliva, are enlarged by additions to their free edges. They advance to meet each other and soon join; it is wonderful to see each insect, following its individual initiative, profit by every twig or fragment capable of bearing any weight, in order to enlarge the overhanging ledges.

Individual skill and reflection. — This personality in work, which reveals the intelligent effort of each, has certainly its inconveniences for the common work. Badly-concerted operations may not succeed, and Huber witnessed an accident due to this cause.[105] Two walls facing each other were to be united by an arch. A foolish worker had begun to form a horizontal ledge on the summit of one of the walls without paying attention to the fact that the other wall was very much higher. By continuing the project the ceiling would have come against the middle of the opposite ceiling instead of resting on its summit. Another ant passes, examines affairs with an intelligent air, and evidently considers that this sort of work is absurd. Without consideration for the amour-propre of its unskilful fellow-citizen, it demolishes its work, raises the wall that is too low, and re-makes the construction correctly in the presence of the observer. If this incident reveals inconceivable thoughtlessness in one of the members of this serious republic, it also brings to light the judgment, reflection, and decision of which they are capable, as well as a freedom which cannot be found in the works of instinct.

This Formica fusca sometimes finds itself in the presence of other difficulties. It may happen that the hall to be roofed is too large and the arch too considerable to allow of the cohesion of the materials employed. The insects soon become aware of the existence of this embarrassing state of things and remedy it in various ways, either by hastily constructing pillars in the centre of the too large room, or by some other method. Ebrard describes an artifice he has seen employed, which shows to what an extent ants can quickly appreciate and take advantage of the most unforeseen circumstances.[106] A worker was labouring to cover a large cell; two prominences, parts of opposite walls, were advancing towards each other, but there was still a space of from twelve to fifteen millimetres between them, and it seemed no longer possible to burden the two sides without risking a general downfall. The little mason was much disturbed. A graminaceous plant was growing near. The ant seemed anxious to take advantage of it, for it went to it and climbed up the stalk. After having examined and devised, it set about curving it in the direction of the edifice. To attain this object, it placed a little mass of moist earth on the extremity of the leaf, and fixed it there. Under the influence of this weight flexion was produced, but only at the end. This could not satisfy the insect; it became a question of decreasing the resistance at the base. The ant gnawed a little at this spot; the desired result was attained, and the whole length of the leaf became bent over the building in course of construction. To prevent it bending back, and to ensure its remaining adherent to the roof, the worker returned to the plant and placed earth between the sheath and the stalk. This time all difficulties were surmounted, and there was a solid scaffolding to support the materials for the roof.