The great Anthropoid Apes have found nothing better for shelter than the Squirrels' method. It must, however, be taken into account that they have much more difficulty in arranging and maintaining much heavier rooms, and in building up a shelter with larger surface.

The Orang-outang, which lives in the virgin forests of the Sunda Archipelago, does not feel the need of constructing a roof against the rain. He is content with a floor established in the midst of a tree, and made of broken and interlaced branches. He piles up on this support a considerable mass of leaves and moss; for the Orang does not sleep seated like the other great apes, but lies down in the manner of Man, as has often been observed when he is in captivity. When he feels the cold he is ingenious enough to cover himself with the leaves of his couch.

In Upper and Lower Guinea the Chimpanzee (Troglodytes niger) also establishes his dwelling on trees. He first makes choice of a large horizontal branch, which constitutes a sufficient floor for the agile animal. Above this branch he bends the neighbouring boughs, crosses them, and interlaces them so as to obtain a sort of framework. When this preliminary labour is accomplished, he collects dead wood or breaks up branches and adds them to the first. Before commencing he had taken care when choosing the site that the whole was so arranged that a fork was within reach to sustain the roof. He thus constructs a very sufficient shelter. These apes are sociable and prefer to live in each other's neighbourhood. They even go on excursions in rather large bands. Notwithstanding this, more than one or two cabins are never seen on the same tree; perhaps this is because the complicated conditions required for the construction are not likely to be realised several times on the same tree; perhaps also it is a desire for independence which impels the Chimpanzees not to live too near to each other.[92]

[92] Savage, "Observations on the External Characters and Habits of the Troglodytes niger," Boston Journal Nat. Hist., 1843, pp. 362-376.

The Troglodytes calvus, a relative of the preceding, inhabiting the same regions, as described by Du Chaillu, shows still more skill in raising his roof. A tree is always chosen for support. He breaks off boughs and fastens them by one end to the trunk, by the other to a large branch. To fix all these pieces he employs very strong creepers, which grow in abundance in his forests. Above this framework, which indicates remarkable ingenuity, the animal piles up large leaves, forming in layers well pressed down and quite impenetrable to the rain. The whole has the appearance of an open parasol. The ape sits on a branch beneath his handiwork, supporting himself against the trunk with one arm. He has thus an excellent shelter against the mid-day sun as well as against tropical showers. Male and female each possess a dwelling on two neighbouring trees, the principle of conjugal cohabitation not being admitted in this species. As to the child, it appears that it sleeps near its mother, until it is of age to lead an independent life.

There exists in Australia, the country of zoological singularities, a bird with very curious customs. This is the Satin Bower-bird. The art displayed in this bird's constructions is not less interesting than the sociability he gives evidence of, and his desire to have for his hours of leisure a shelter adorned to his taste. The bowers which he constructs, and which present on a small scale the appearance of the arbours in our old gardens, are places for re-union and for warbling and courtship, in which the birds stay during the day, when no anxiety leads them to disperse. They are not, properly speaking, nests built for the purpose of rearing young; for at the epoch of love each couple separates and constructs a special retreat in the neighbourhood of the bower. These shelters are always situated in the most retired parts of the forest, and are placed on the earth at the foot of trees. Several couples work together to raise the edifice, the males performing the chief part of the work. At first they establish a slightly convex floor, made with interlaced sticks, intended to keep the place sheltered from the moisture of the soil. The arbour rises in the centre of this first platform. Boughs vertically arranged are interlaced at the base with those of the floor. The birds arrange them in two rows facing each other; they then curve together the upper extremities of these sticks, and fix them so as to obtain a vault. All the prominences in the materials employed are turned towards the outside, so that the interior of the room may be smooth and the birds may not catch their plumage in it. This done, the little architects, to embellish their retreat, transport to it a number of conspicuous objects, such as very white stones from a neighbouring stream, shells, the bright feathers of the parroquet, whatever comes to their beak. All these treasures are arranged on the earth, before the two entries to the bower, so as to form on each side a carpet, which is not smooth, but the varied colours of which rejoice the eye. The prettiest treasures are fixed into the wall of the hut. These houses of pleasure, with all their adornments, form a dwelling very much to the taste of this winged folk, and the birds pass there the greater part of the day, preening their feathers and narrating the news of the forest. Bower-birds' clubs are drawing-rooms raised at the common expense by all who frequent them. The Spotted Bower-bird, the Chlamydera maculata, which also lives in the interior of Australia, exercises this method of construction with equal success. The bowers built by these birds may be one metre in length; this is on a very luxurious scale, the animal itself only measuring twenty-five centimetres. In this species, as among other Bower-birds, the bowers are not the labour and the property of a single couple; they are the result of the collaboration of several households, who come together to shelter themselves there. These birds feed only on grains, so that it is to a very pronounced taste for collecting that we must attribute this mania of piling up before the entrance of the bower white stones, shells, and small bones. (Fig. 25.) These objects are intended solely for the delight of these feathered artists. They are very careful also only to collect pieces which have been whitened and dried by the sun.[93]

[93] Gould first accurately described the habits of the Bower-birds, Proceed. Zool. Soc.; London, 1840, p. 94; also Handbook to the Birds of Australia (1865), vol. i. pp. 444-461. See also Darwin's Descent of Man (1881), pp. 381 and 413-414.

Certain Humming-birds also, according to Gould, decorate their dwellings with great taste. "They instinctively fasten thereon," he stated, "beautiful pieces of flat lichen, the larger pieces in the middle, and the smaller on the part attached to the branch. Now and then a pretty feather is intertwined or fastened to the outer sides, the stem being always so placed that the feather stands out beyond the surface."[94]

[94] Gould, Introduction to the Trochilidae, 1861, p. 19.

Dwellings woven of flexible substances.—In spite of their lack of skill and the inadequacy of their organs for this kind of work, Fish are not the most awkward architects. The species which construct nests for laying in are fairly numerous; the classical case of the Stickleback is always quoted, but this is not the only animal of its class to possess the secret of the manufacture of a shelter for its eggs.

A fish of Java, the Gourami (Osphronemus olfax), establishes an ovoid nest with the leaves of aquatic plants woven together. It makes its work about the size of a fist, takes no rest until it is completed, and is able to finish it in five or six days. It is the male alone who weaves this dwelling; when it is ready a female comes to lay there, and generally fills it; it may contain from six hundred to a thousand eggs.



In the sea of Sargasso lives a fish which has received the name of the Antennarius marmoratus. Its flattened and monstrous head gives it a strange aspect, and it is marbled with brown and yellow. These colours are those of the tufts of floating seaweed around it, and, thanks to this arrangement, it can easily hide itself amid them without being recognised from afar. This animal constructs for its offspring a fairly safe retreat. The materials which it employs are tufts of Sargasso so abundant in this portion of the Atlantic. It collects all the filaments, and unites them solidly by surrounding them with viscous mucus which it secretes and which hardens. When its work is sufficiently firm not to be destroyed by the waves it lays its eggs in it, and the floating nest is abandoned to its fate. The little ones come out and find within it a sufficient protection for their early age. These dwellings thus floating on the surface of the sea are rounded and about the size of a cocoa-nut.

In Guiana and Brazil another species, the Choestostomus pictus, is found, which is equally skilful. With aquatic plants it constructs a spherical nest and arranges it in the midst of the reeds, level with the water. At the lower part a hole is left, through which the female comes to lay. After fertilisation, the couple, as is rarely found among fish, remain in the neighbourhood of their offspring to assist them if necessary. This praiseworthy sentiment is often the cause of their ruin. The inhabitants of the banks speculate on the love of these fish for their offspring to gain possession of them. It is sufficient to place a basket near the entrance of the dwelling, which is then lightly struck. The animal, threatened in its affections, darts furiously forward with bristling spines and throws itself into the trap.

It is scarcely necessary to recall the skilful art with which the Stickleback which inhabits all our streams plaits its nest and remains sentinel near it. (Fig. 26.) This fish has indeed monopolised our admiration, and is considered as the most skilful, if not the only aquatic architect. Yet, besides those which I have already mentioned, there is one which equals the Stickleback in the skill it displays in constructing a shelter for its spawn. This is the Gobius niger met on our coasts, especially in the estuaries of rivers. The male interlaces and weaves the leaves of algae, etc., and when he has finished his preparations, he goes to seek females, and leads them one by one to lay in the retreat he has built. Then he remains in the neighbourhood until the young come out, ready to throw himself furiously with his spines on any imprudent intruders.



Dwellings woven with greater art.—Without doubt the class of Birds furnishes the most expert artisans in the industry of the woven dwelling. In our own country we may see them seeking every day to right and left, carrying a morsel of straw, a pinch of moss, a hair from a horse's tail, or a tuft of wool caught in a bush. They intermingle these materials, making the framework of the construction with the coarser pieces, keeping those that are warmer and more delicate for the interior. These nests, attached to a fork in a branch or in a shrub, hidden in the depth of a thicket, are little masterpieces of skill and patience. To describe every form and every method would fill a volume. But I cannot pass in silence those which reveal a science sure of itself, and which are not very inferior to what man can do in this line. The Lithuanian Titmouse (AEgithalus pendulinus), whose works have been well described by Baldamus, lives in the marshes in the midst of reeds and willows in Poland, Galicia, and Hungary. Its nest, which resembles none met in our own country, is always suspended above the water, two or three metres above the surface, fixed to a willow branch.[95] All individuals do not exhibit the same skill in fabricating their dwelling; some are more careful and clever than others who are less experienced. Some also are obliged by circumstances to hasten their work. It frequently happens that Magpies spoil or even altogether destroy with blows of their beaks one of these pretty nests. The unfortunate couple are obliged to recommence their task, and if this accident happens two or three times to the same household, it can easily be imagined that, discouraged and depressed by the advancing season, they hasten to build a shelter anyhow, only doing what is indispensable, and neglecting perfection. However this may be, the nests which are properly finished have the form of a purse, twenty centimetres high and twelve broad. (Fig. 27.) At the side an opening, prolonged by a passage which is generally horizontal, gives access to the interior. Sometimes another opening is found without any passage. Every nest in the course of construction possessed this second entry, but it is usually filled up when the work is completed. When the bird has resolved to establish its retreat, it first chooses a hanging branch presenting bifurcations which can be utilised as a rigid frame on which to weave the lateral walls of the habitation. It intercrosses wool and goat's hair so as to form two courses which are afterwards united to each other below, and constitute the first sketch of the nest, at this moment like a flat-bottomed basket. This is only the beginning. The whole wall is reinforced by the addition of new material. The architect piles up down from the poplar and the willow, and binds it all together with filaments torn from the bark of trees, so as to make a whole which is very resistant. Then a couch is formed by heaping up wool and down at the bottom of the nest.

[95] Baldamus, Beitraege zur Oologie und Nidologie, 1853, pp. 419-445.

The American Baltimore Oriole, also called the Baltimore Bird, is a distinguished weaver. With strong stalks and hemp or flax, fastened round two forked twigs corresponding to the proposed width of nest, it makes a very delicate sort of mat, weaving into it quantities of loose tow. The form of the nest might be compared to that of a ham; it is attached by the narrow portion to a small branch, the large part being below. An opening exists at the lower end of the dwelling, and the interior is carefully lined with soft substances, well interwoven with the outward netting, and it is finished with an external layer of horse-hair, while the whole is protected from sun and rain by a natural canopy of leaves.

The Rufous-necked Weaver Bird, as described by Brehm, shows itself equally clever. Its nest is woven with extreme delicacy, and resembles a long-necked decanter hung up with the opening below. From the bottom of the decanter a strong band attaches the whole to the branch of a tree. (Fig. 28.) The Yellow Weaver Bird of Java, as described by Forbes, constructs very similar retort-shaped nests.[96]

[96] H. O. Forbes, A Naturalist's Wanderings in the Eastern Archipelago, 1885, pp. 56-58.

These birds have no monopoly of these careful dwellings; a considerable number of genera have carried this industry to the same degree of perfection.



When animals apply themselves in association to any work, they nearly always exhibit in it a marked superiority over neighbouring species among whom the individuals work in isolation. The construction of dwellings is no exception, and the nests of the Sociable Weaver Birds of South Africa are the best constructed that can be found. These birds live together in considerable colonies; the members of an association are at least two hundred in number, and sometimes rise to five hundred. The city which they construct is a marvel of industry. They first make with grass a sloping roof; giving it the form of a mushroom or an open umbrella, and they place it in such a way that it is supported by the trunk of a tree and one or two of the branches. (Fig. 29.) This thatch is prepared with so much care that it is absolutely impenetrable to water. Beneath this protecting shelter each couple constructs its private dwelling. All the individual nests have their openings below, and they are so closely pressed against one another that on looking at the construction from beneath, the divisions cannot be seen. One only perceives a surface riddled with holes like a skimmer; each of these holes is the door of a nest. The work may endure for several years; as long as there is room beneath the roof the young form pairs near their cradle; but at last, as the colony continues to increase, a portion emigrate to found a new town on another tree in the forest.[97]

[97] An early description of this bird is to be found in W. Paterson's Narrative of Four Journeys into the Country of the Hottentots, 1789; also in Le Vaillant's Second Voyage dans l'interieur de l'Afrique, 1803, t. iii., p. 322.



The industry of the woven dwelling does not flourish among mammals; but there is one which excels in it. This is the Dwarf Mouse (Mus minutus), certainly one of the smallest Rodents. It generally lives amidst reeds and rushes, and it is perhaps this circumstance which has impelled it to construct an aerial dwelling for its young, not being able to deposit them on the damp and often flooded soil. This retreat is not used in every season; its sole object is for bringing forth the young. It is therefore a genuine nest, not only by the manner in which it is made, but by the object it is intended to serve. The mouse chooses in the midst of its usual domain a tuft with leaves more or less crossed; but not too inextricable, so that there may remain in the midst an empty space, in the centre of which the work will be arranged. Great ingenuity is shown in the preliminaries; the mouse simplifies its task by utilising material within its reach instead of going afar to collect them with trouble. The little animal examines the thicket, and on reflection chooses some thirty leaves which appear suitable. Then, without detaching them, it tears each into seven or eight threads which are held together by the base, and remain attached to the reeds. It is a clever idea to avoid losing a natural point of support. The little bands being thus prepared, they are interlaced and crossed with much art, the animal comes and goes, placing first one of them, then another above, taken from a different leaf. It has soon woven a ball about the size of the fist, and hollowed out the interior. (Fig. 30.) Delicate materials are not lacking around to make a soft bed. The mouse gleans and constantly brings in the light down of the willow, grains with cottony crests, and the petals of flowers. This is all carefully fitted, and when the edifice is completed the female retires into it to bring forth her young, which are there well sheltered against the dangers without, and the caprices of storms and floods. The nest is made with as much delicacy as that of any bird, and no other mammal except Man is capable of executing such weaver's work.

The art of sewing among birds.—There are birds which have succeeded in solving a remarkable difficulty. Sewing seems so ingenious an art that it must be reserved for the human species alone. Yet the Tailor Bird, the Orthotomus longicauda, and other species possess the elements of it. They place their nests in a large leaf which they prepare to this end. With their beaks they pierce two rows of holes along the two edges of the leaf; they then pass a stout thread from one side to the other alternately. With this leaf, at first flat, they form a horn in which they weave their nest with cotton or hair. (Fig. 31.) These labours of weaving and sewing are preceded by the spinning of the thread. The bird makes it itself by twisting in its beak spiders' webs, bits of cotton, and little ends of wool. Sykes found that the threads used for sewing were knotted at the ends.[98] It is impossible not to admire animals who have skilfully triumphed over all the obstacles met with in the course of these complicated operations.[99]

[98] Catalogue of Birds, etc., p. 16.

[99] Tristram, "On the Ornithology of Northern Africa," Isis, 1859-60.



Certain Spiders, while they do not actually sew in the sense that they perforate the leaves they use to build their nest, and draw the thread through them, yet subject the leaves to an operation which cannot well be called anything else but sewing it.[100]

[100] McCook describes, and gives good illustrations of, these nests in various stages of progress, American Spiders, vol i. p. 302.

Modifications of dwellings according to season and climate.—A certain number of facts show that these various industries are not fixed and immutable instincts imposed on the species. Certain Birds change the form of their dwelling according to the climate, or according to the season in which they inhabit it. For example, the Crossbill, Loxia taenioptera (Fig. 32), does not build its nest according to the same rules in Sweden as in France. It builds in every season. The winter shelter is spherical, constructed with very dry lichens, and it is very large. A very narrow opening, just sufficient for the passage of the owner, prevents the external cold from penetrating within. The summer nests are much smaller, in consequence of a reduction in the thickness of the walls. There is no longer need to fear that the cold will come through them, and the animal gives itself no superfluous trouble.



Again, the Baltimore Oriole, which inhabits both the Northern and Southern States of North America, knows very well how to adapt his manner of work to the external circumstances in which he lives. Thus, in the Southern States the nest is woven of delicate materials united in a rather loose fashion, so that the air can circulate freely and keep the interior fresh; it is lined with no warm substance, and the entrance is turned to the west so that the sun only sends into it the oblique evening rays. In the north, on the contrary, the nest is oriented to the south to profit by all the warm sunshine; the walls are thick, without interstices, and the dwelling is carpeted in the warmest and softest manner. Even in the same region there is great diversity in the style, neatness, and finish of the nests, as well as in the materials used. Skeins of silk and hanks of thread have frequently been found in the Baltimore Bird's nest, so woven up and entangled that they could not be withdrawn. As such materials could not be obtained before the introduction of Europeans, it is evident that this bird, with the sagacity of a good architect, knows how to select the strongest and best materials for his work. Many other facts might be quoted, but these suffice to show that the species is not animated by an inevitable instinct, but that each individual, skilful no doubt by heredity, can modify the methods transmitted to him by his ancestors, according to his own experience and his own judgment.

Built dwellings.—The built dwelling, the expression of the highest civilisation, still remains to be studied. Man has only known how to construct this kind of shelter at a comparatively late period in his evolution; and among animals we do not find it widely spread, much less so, certainly, than the two foregoing methods, especially the first. The difficulty of this work is greater, and it only arrives at considerable development among very sociable species, since the united efforts of a great number of individuals are needed to carry it on.

There are, however, masons who operate separately; but their constructions are rudimentary. The characteristic of all these works is that they are manufactured with some substance to which the animal gives a determined form while it is still soft, and that in drying it preserves this form and acquires solidity. The matter most usually employed is softened and tempered earth—mortar; but there are animals who use with success more delicate bodies. Two examples will suffice to indicate the nature of these exceptions: the labours of Wasps and those of certain Swallows.



Paper nests.—Certain Wasps, by the material of their dwellings, approach the Japanese; they build with paper. This paper or cardboard is very strong and supplies a solid support; moreover, being a bad conductor of heat, it contributes to maintain an equable temperature within the nest. The constructions of these insects, though they do not exhibit the geometric arrangement of those of Bees, are not less interesting. The paper which they employ is manufactured on the spot, as the walls of the cells develop. Detritus of every kind enters into its preparation: small fragments of wood, sawdust, etc.; anything is good. These Hymenoptera possess no organ specially adapted to aid them; it is with their saliva that they glue this dust together and make of it a substance very suitable for its purpose. The dwellings often reach considerable size, yet they are always begun by a single female, who does all the work without help until the moment when the first eggs come out; she is thus furnished with workers capable of taking a share in her task. The Vespa sylvestris builds a paper nest of this kind, hanging to the branch of a tree, like a great grey sphere prolonged to a blunt neck. (Fig. 33.) The Hornet's nest is similar in construction.

Gelatine nests.—These are made by certain Swallows who nest in grottoes or cliffs on the edge of the sea. After having collected from the water a gelatinous substance formed either of the spawn of fish or the eggs of Mollusca, they carry this substance on to a perpendicular wall, and apply it to form an arc of a circle. This first deposit being dry, they increase it by sticking on to its edge a new deposit. Gradually the dwelling takes on the appearance of a cup and receives the workers' eggs. (Fig. 34.) These dwellings are the famous swallows' nests, so appreciated by the epicures of the extreme East, which are edible in the same way as, for example, caviare.

Constructions built of earth—Solitary masons.—Certain animals, whose dwelling participates in the nature of a hollow cavern, make additions to it which claim a place among the constructions with which we are now occupied.



The Anthophora parietina is in this group; it is a small bee which lives in liberty in our climate. As its name indicates, it prefers to frequent the walls of old buildings and finds a refuge in the interstices, hollowing out the mortar half disintegrated by time. The entrance to the dwelling is protected by a tube curved towards the bottom, and making an external prominence. (Fig. 35.) The owner comes and goes by this passage, and as it is curved towards the earth the interior is protected against a flow of rain, while at the same time the entry is rendered more difficult for Melectes and Anthrax. These insects, in fact, watch the departure of the Anthophora to endeavour to penetrate into their nests and lay their eggs there. The gallery of entry and exit has been built with grains of sand, the debris produced by the insect in working. These grains of sand glued together form, on drying, a very resistant wall.[101]

[101] Latreille, "Observations sur l'abeille parietine (Anthophora parietina)," Annales du Museum d'Hist. Nat., t. iii., 1804, p. 257.

The other animals of which I have to speak are genuine masons, who prepare their mortar by tempering moistened earth. Every one has seen the Swallow in spring working at its nest in the corner of a window. It usually establishes its dwelling in an angle, so that the three existing walls can be utilised, and to have an enclosed space there is need only to add the face. It usually gives to this the form of a quarter of a sphere, and begins it by applying earth more or less mixed with chopped hay against the walls which are to support the edifice. At the summit of the construction a hole is left for entry and exit. During the whole of its sojourn in our country the Swallow uses this dwelling, and even returns to it for many years in succession, as long as its work will support the attacks of time. The faithful return of these birds to their old nest has been many times proved by attaching ribbons to their claws; they have always returned with the distinctive mark.



The Chalicodoma, whose name of Mason Bee indicates the industry it exercises, is a hymenopterous relative to our Bees, long since carefully studied by Reaumur. It does not live in societies like the latter, and exhibits individual initiative and skill as great as the swallows. The females accomplish the work which I am about to describe. The little cells which they build are arranged, to the number of eight or ten together, in the most various places; sometimes on a pebble, sometimes on a branch, or, again, on a stone wall. (Fig. 36.) The insect collects earth as fine as possible, such as the dust of a trodden path, and tempers it with its own saliva. It places side by side these little balls of mortar and the work soon takes the form of a cupola, to the edge of which it constantly adds new deposits. The sun quickly dries the hole and gives it the necessary consistence. When the cell has acquired sufficient height, the Chalicodoma abandons its occupation of mason, and visits flowers for pollen and nectar wherewith to fill the little chamber. It goes back to the nest, disgorges its supply, and returns to the field, until the little cup of earth is full to the edge. When the dwelling is thus prepared and provisioned, the insect lays an egg there and closes the upper part with a vault, built by successive deposits over the opening, which is more and more narrowed until it is finally shut up. Having completed a chamber, it passes on to the next, and so on until it has assured the fate of all its descendants.

This hymenopterous insect certainly shows in its acts as an artisan an inevitable instinct: hereditary intelligence has become less personal and less spontaneous. In certain cases, however, the instinct loses its rigidity and automatism. Thus, when a Chalicodoma, at the moment of preparing to accomplish its task, finds an old nest, still capable of repair although dilapidated, it does not hesitate to take possession of it and to silence its assumed innate instinct of building. It profits by the work already done, and is content to fill up the cracks or to re-establish the masonry where defective; then it provisions the renewed cells with honey, and lays its eggs in them. In certain circumstances it shows itself still more sparing of trouble, and boldly rebels against the law which seems to be imposed on it by nature. If it feels itself sufficiently strong, the Chalicodoma throws itself on one of its fellows, a peaceful constructor that has almost completed its work; it chases it away, and takes possession of its property to shelter its own eggs. Instead of manufacturing the cell from bottom to top, it has only to complete it. Such acts evidently show the reflection appearing through instinct.

Besides the Swallows, of which I have already spoken, birds offer us several types of skilful construction with tempered earth.

The Flamingo, which lives in marshes, cannot place its eggs on the earth nor in the trunks of trees, which are often absent from its domain. It builds a cone of mud, which dries and becomes very resistant, and it prepares at the summit an excavation open to the air; this is the nest. The female broods by sitting with her legs hanging over the sides of the hillock on which her little family prospers above the waters and the damp soil.

A Perch in the Danube also manufactures a dwelling of dried earth. It gives it the form of an elliptic cupola, and prepares a semicircular opening for entry and exit.

The bird which shows itself the most skilful mason is probably the Oven-Bird (Furnarius rufus) of Brazil and La Plata. Its name is owing to the form of the nest which it constructs for brooding, and which has the appearance of an oven. It is very skilful and knows how to build a dome of clay without scaffolding, which is not altogether easy. Having chosen for the site of its labours a large horizontal branch, it brings to it a number of little clay balls more or less combined with vegetable debris, works them altogether, and makes a very uniform floor, which is to serve as a platform for the rest of the work. When this is done, and while the foundation is drying, the bird arranges on it a circular border of mortar slightly inclined outwards. This becomes hard; it raises it by a new application, this time inclined inwards. All the other layers which will be placed above this will also be inclined towards the interior of the chamber. As the structure rises, the circle which terminates it above becomes more and more narrow. Soon it is quite small, and the animal, closing it with a little ball of clay, finds itself in possession of a well-made dome. Naturally it prepares an entrance; the form of this is semicircular. But this is not all. In the interior it arranges two partitions: one vertical, the other horizontal, separating off a small chamber. The vertical partition begins at one of the edges of the door, so that the air from without cannot penetrate directly into the dwelling, which is thus protected against extreme variations of temperature. It is in the compartment thus formed that the female lays her eggs and broods, after having taken care to carpet it with a thick layer of small herbs.

"In favourable seasons, the Oven-birds begin building in the autumn," Hudson tells us, "and the work is resumed during the winter whenever there is a spell of mild, wet weather. Some of their structures are finished early in winter, others not until spring, everything depending on the weather and the condition of the birds. In cold, dry weather, and when food is scarce, they do not work at all. The site chosen is a stout horizontal branch, or the top of a post, and they also frequently build on a cornice or the roof of a house; and sometimes, but rarely, on the ground. The material used is mud, with the addition of horse hair or slender fibrous rootlets, which make the structure harder and prevent it from cracking. I have frequently seen a bird engaged in building first pick up a thread or hair, then repair to a puddle, where it was worked into a pellet of mud about the size of a filbert, then carried to the nest. When finished the structure is shaped outwardly like a baker's oven, only with a deeper and narrower entrance. It is always placed very conspicuously, and with the entrance facing a building, if one be near, or if at a roadside it looks towards the road; the reason for this being, no doubt, that the bird keeps a continuous eye on the movements of people near it while building, and so leaves the nest opened and unfinished on that side until the last, and then the entrance is necessarily formed. When the structure has assumed the globular form with only a narrow opening, the wall on one side is curved inwards, reaching from the floor to the dome, and at the inner extremity an aperture is left to admit the bird to the interior or second chamber, in which the eggs are laid. A man's hand fits easily into the first or entrance chamber, but cannot be twisted about so as to reach the eggs in the interior cavity, the entrance being so small and high up. The interior is lined with dry soft grass, and five white pear-shaped eggs are laid. The oven is a foot or more in diameter, and is sometimes very massive, weighing eight or nine pounds, and so strong that, unless loosened by the swaying of the branch, it often remains unharmed for two or three years. A new oven is built every year, and I have more than once seen a second oven built on the top of the first, when this has been placed very advantageously, as on a projection and against a wall."[102]

[102] P. L. Sclater and W. H. Hudson, Argentine Ornithology, 1888, vol. i. pp. 168, 169. See also Burmeister, "Ueber die Eier und Nester einiger brasilianischen Voegel," Cabani's Journal fuer Ornith., 1853, pp. 161-177.

Masons working in association.—Ants have already furnished us with numerous proofs of their intelligence and their prodigious industry. So remote from Man from the anatomical point of view, they are of all animals those whose psychic faculties bring them nearest to him. Sociable like him, they have undergone an evolution parallel to his which has placed them at the head of Insects in the same way as he has become superior to all other Mammals. The brain in Ants as in Man has undergone a disproportionate development. Like Man, they possess a language which enables them to combine their efforts, and there is no human industry in which these insects have not arrived at a high degree of perfection. If in certain parts of the earth human societies are superior to those of Ants, in many others the civilisation of Ants is notably superior. No village of Kaffirs can be compared to a palace of the Termites. The classifications separate these insects (sometimes called "White Ants") from the Ants, since the latter are Hymenoptera, while the former are ranked among the Neuroptera, but their constructions are almost alike, and may be described together. These small animals, relatively to their size, build on a colossal scale compared to Man; even our most exceptional monuments cannot be placed beside their ordinary buildings. (Fig. 37.) The domes of triturated and plastered clay which cover their nests may rise to a height of five metres; that is to say, to dimensions equal to one thousand times the length of the worker. The Eiffel Tower, the most elevated monument of which human industry can boast, is only one hundred and eighty-seven times the average height of the worker. It is three hundred metres high, but to equal the Termites' audacity, it would have to attain a height of 1,600 metres.



The different species of Termite are not equally industrious. The T. bellicosus seems to have carried the art of construction to the highest point. All the individuals of the species are not alike; there exists a polymorphism which produces creatures of three sorts: 1, the soldiers, recognised by their large heads and long sharp mandibles, moved by powerful muscles; it is their mission to defend the whole colony against its adversaries, and the wounds they can produce, fatal to creatures of their own size, are painful even to man; 2, the workers, who labour as navvies and architects, and take charge of the pupae: they form the great majority of the community; 3, the king and queen. (Fig. 38.) To each nest there is usually only a single fertile and lazy couple. These two personages do absolutely nothing; the soldiers and the workers care for them and bring them food. They have both possessed wings, but these fall off. The queen reigns but does not govern; she lays. The king is simply the husband of the queen. The internal administration of the palace is bound up with the parts played by these three kinds of beings.



The lofty nest, or Termitarium, constitutes a hillock in the form of a cupola. The interior arrangement is very complicated, and at the same time very well adapted to the life of the inhabitants. There are four storeys in all, covered by the general exterior walls. (Fig. 39.) The walls of the dome are very thick; at the base they measure from sixty to eighty centimetres. The clay in drying attains the hardness of brick, and the whole is very coherent. The sentinels of herds of wild cattle choose these tumuli as observatories and do not break them down. The walls of this exterior enceinte are hollowed by galleries of two kinds: some horizontal and giving access from outside to all the storeys; the others mounting spirally in the thickness of the wall to the summit of the dome. When the colony is in full activity, after the construction is completed, these little passages have no further use. They served for the passage of the masons when building the cupola; and they could be utilised again if a breach should be made in the wall. At the lower part these galleries in the wall are very wide, and they sink into the earth beneath the palace to a depth of more than 1 metre 50.

These subterranean passages (c) are the catacombs of the Termites, and have a very close analogy with those of old and populous human cities. Their origin is similar; they are ancient quarries. The insects hollowed them in obtaining the necessary clay for their labours. Later, when the rains come, they serve as drains to carry off the water which might threaten to invade the dwelling.

Such is the external wall within which a busy population swarms. On passing to the interior let us first enter the ground-floor. In the centre is found the royal chamber (r). The walls are extremely strong and are supplied with windows for ventilation, and with doors to enable the Termites to render their services. It is necessary to renew the air in this chamber, which constantly contains more than two thousand insects. The openings are large enough for the passage of the workers, but the queen cannot pass through them. She is therefore a prisoner, as immured as a goddess in her temple. The chain which holds her is the prodigious development of her abdomen. As a virgin she could enter, when fertilised she cannot henceforth go out. She continuously elaborates eggs; every moment one appears at the orifice of the oviduct. The king remains near her, to give his assistance when occasion arises; hence he has received the title, absolutely justified under the circumstances, of Father of the People. Around the couple zealous attendants crowd. There are about two thousand of them, workers and soldiers, licking the two royal captives to remove any dust from their hairs, and bringing them food. As soon as the queen lays an egg, one of the workers hastens to take it gently between its jaws; it is the property of the state, and is carefully carried off to the second storey where the state nursery is situated.

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 larvae 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 larvae 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]

[103] The earliest comprehensive account of the Termites and their industries was by Smeathman in the Philosophical Transactions of the Royal Society, vol. lxxi., 1781, pp. 139-192. Later they were studied by Lespes: "Recherches sur l'organisation et les moeurs du Termite lucifuge," Ann. des Sci. Nat., 4me Serie, t. v., fasc. 4 and 5, Paris, 1856. For a description of the South American Termitarium see also Bates's Naturalist on the Amazons (unabridged edition, 1892), pp. 208-214; and for the African Termites of Victoria Nyanza, a chapter in H. Drummond's Tropical Africa, 1888, pp. 123-158; while Forbes has briefly described them in Java, Naturalist's Wanderings in the Eastern Archipelago, pp. 73, 74.

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 antennae 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 manoeuvre 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.

[104] For a discussion of the methods of communication among Ants, tending to the conclusion that these methods "almost amount to language," see Lubbock's Ants, Bees, and Wasps, chap. vi. And for a general discussion of language among animals, see Alix, L'esprit de nos Betes, pp. 331-367.

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.

[105] Recherches sur les Moeurs des Fourmis indigenes, pp. 47, 48.

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.

[106] Ebrard, Etudes de Moeurs, Geneve, 1864, p. 3.

Among the Lasius niger the independence of the workers is perhaps still greater; no doubt they do their best to concert their efforts, but they do not succeed so well as if an inevitable instinct impelled them. Notwithstanding the irregularities of the construction, it is possible to recognise in it a whole formed of hollowed, concentric half-spheres; they have been added one after the other to the surface to increase the dwelling. The interval between these clay spheres constitutes a storey, cut up by the partitions which divide it into chambers and communicating galleries; the roofs of the largest halls are supported by numerous pillars. (Fig. 40.)



These ants, as Huber has shown, are highly accomplished in the art of constructing a cupola. When they wish to increase their nest by a new layer, they take advantage of the first wet day, the rain serving to agglutinate and unite the materials. They operate in almost the same way as the Formica fusca, though exhibiting more skill and resource as architects; they know better how to calculate beforehand the number of pillars required in a hall of a determined size. As soon as the rain has given the signal for work, they spread themselves abroad and prepare a very thick terrace on the external surface of the dwelling which has become too small. They carry to it small balls of earth ground very fine by their jaws, and then lightly piled up so as to pulverise afresh; these are then spread over the construction with the anterior legs. Then, by hollowing out, the ants trace the plan of the new storey, leaving the walls, partitions, and columns in relief. After having raised these parts to a sufficient height, all work together to cover them with a general ceiling, each ant applying itself to one small corner of the work.

The vaulting is executed by the method already described; horizontal ledges, slanting from the summit of pillar or wall, are formed to meet one another. The insects are intelligent enough to begin their labour at the spots best fitted to give strong support to the overhanging materials, as for instance, at the angle of two walls. There is so much activity among the workers, and they are so anxious to take advantage of the damp, that the storey is sometimes completely finished in seven or eight hours. If the rain suddenly stops in the course of the work, they abandon operations, to complete them as soon as another shower falls.

I have already had occasion to speak of the covered passages and Aphis-pens built by Ants outside their dwellings. Besides these constructions, they also make roads in the fields, tearing up the grass and hollowing out the earth so as to form a beaten path free from the lilliputian bushes in which there would be danger of becoming entangled, on returning to the nest laden with various and often embarrassing burdens.

Nor are Ants by any means alone in exhibiting the results of individual skill and reflection. It will, however, be sufficient to mention only one other example, that furnished by Spiders. McCook, in his great work, after elaborately describing and carefully illustrating the skill exhibited in individual cases by Spiders in their aerial labours, considers himself justified in concluding as follows:—"The manner in which the ends of the radii which terminate upon the herb are wrapped roundabout and braced by the notched zone; the manner in which the wide non-viscid scaffold lines are woven in order to give vantage ground from which to place the close-lying and permanent viscid spirals, upon which the usefulness of the orb depends—all these, to mention no other points, seem to indicate a very delicate perception of those modes (shall I also say principles?) of construction which are continually recognised in the art of the builder, the architect, and the engineer."[107]

[107] American Spiders, vol. i. p. 228.

Dwellings built of hard materials united by mortar.—Among mammals few animals have become so skilful in the art of building houses as the insects we have just been considering. There are, however, two who equal if they do not surpass them—the Musk-rat and its relative, the Beaver.

The Musk-rats of Canada live in colonies on the banks of streams or deep lakes, and construct dwellings which are very well arranged. In their methods we find combined the woven shelter with the house of built earth. Their cabins are established over the highest level of the water and look like little domes. In building them the animals begin by placing reeds in the earth; these they interlace and weave so as to form a sort of vertical mat. They plaster it externally with a layer of mud, which is mixed by means of the paws and smoothed by the tail. At the upper part of the hut the reeds are not pressed together or covered with earth, so that the air may be renewed in the interior. A dwelling of this kind, intended to house six or eight individuals who have combined to build it, may measure up to 65 centimetres in diameter. There is no door directly opening on to the ground. A subterranean gallery starts from the floor and opens out beneath the water. It presents secondary branches, some horizontal, through which the animal goes in search of roots for food, while others descend vertically to pits specially reserved for the disposal of ordure.

But it is, above all, the Beaver (Castor fiber) who exhibits the highest qualities as an engineer and mason. This industrious and sagacious Rodent is well adapted to inconvenience the partisans of instinct as an entity, apart from intelligence, which renders animals similar to machines and impels them to effect associated acts, without themselves being able to understand them, and with a fatality and determination from which they can under no circumstance escape.

Beavers now only live in Canada. A few individuals may, however, still be found on the banks of the lower Rhone, in Camargue, and on a few other European rivers. Several centuries ago they existed in the neighbourhood of Paris in considerable numbers. The Bievre gained its name from the old French word for Beaver, and its resemblance to the English name, as well as to the German (Biber), is striking. In the sixteenth century, according to Bishop Magnus of Upsala, the Beaver was still common on the banks of the Rhine, the Danube, and on the shores of the Black Sea, and in the North it still exercised great art in its constructions. In the twelfth century it was found in Scotland and Wales. If we go back to ancient times, we find that Herodotus mentions that the Budini who lived in the neighbourhood of the Black Sea used the skins of the Beavers, which abounded there, on the borders of their garments; and in the time of Pliny the Beaver was so common there that he speaks of it as the Pontic Beaver. Fossil remains of the Beaver have also been found throughout Europe in conjunction with those of the Mammoth and other extinct animals.

But the civilisation of the Beaver has perished in the presence of Man's civilisation, or rather of his persecution. In regions where it is tracked and disturbed by Man the Beaver lives in couples, and is content to hollow out a burrow like the Otter's, instead of showing its consummate art. It merely vegetates, fleeing from enemies who are too strong for it, and depriving itself of a dangerous comfort. But when the security of solitude permits these animals to unite in societies, and to possess, without too much fear, a pond or a stream, they then exhibit all their industry.

They build very well arranged dwellings, although at first sight they look like mere piles of twigs, branches, and logs, heaped in disorder on a small dome of mud. At the edge of a pond each raises his own lodge, and there is no work by the colony in common. If, however, there is a question of inhabiting the bank of a shallow stream, certain preliminary works become necessary. The rodents establish a dam, so that they may possess a large sheet of water which may be of fair depth, and above all constant, not at the mercy of the rise and fall of the stream. A sudden and excessive flood is the one danger likely to prove fatal to these dykes; but even our own constructions are threatened under such circumstances.

When the Beavers, tempted by abundance of willows and poplars, of which they eat the bark and utilise the wood in construction, have chosen a site, and have decided to establish a village on the edge of the water, there are several labours to be successively accomplished. Their first desire is to be in possession of a large number of felled trunks of trees. To obtain them they scatter themselves in the forest bordering the stream and attack saplings of from twenty to thirty centimetres in diameter. They are equipped for this purpose. With their powerful incisors, worked by strong jaws, they can soon gnaw through a tree of this size. But they are capable of attacking trees, even more than 100 cc. in circumference and some forty metres in height, with great skill and adaptability; "no better work could be accomplished by a most highly-finished steel cutting tool, wielded by a muscular human arm" (Martin). They operate seated on their hind quarters, and they make their incision in the wood with a feather edge. It was once supposed that they always take care so to direct their wood-cutting task that the tree may fall on the water-side, but this is by no means the case, and appears to be simply due, as Martin points out, to the fact that trees by the water-side usually slope towards the water. The austerity of labour alternates, it may be added, with the pleasures of the table. From time to time the Beavers remove the bark of the fallen trees, of which they are very fond, and feed on it.

Mr. Lewis H. Morgan studied the American Beaver with great care and thoroughness, more especially on the south-west shore of Lake Superior; he devotes fifty pages to the dams, and it is worth while to quote his preliminary remarks regarding them. "The dam is the principal structure of the beaver. It is also the most important of his erections as it is the most extensive, and because its production and preservation could only be accomplished by patient and long-continued labour. In point of time, also, it precedes the lodge, since the floor of the latter and the entrances to its chamber are constructed with reference to the level of the water in the pond. The object of the dam is the formation of an artificial pond, the principal use of which is the refuge it affords to them when assailed, and the water-connection it gives to their lodges and to their burrows in the banks. Hence, as the level of the pond must, in all cases, rise from one to two feet above these entrances for the protection of the animal from pursuit and capture, the surface-level of the pond must, to a greater or less extent, be subject to their immediate control. As the dam is not an absolute necessity to the beaver for the maintenance of his life, his normal habitation being rather natural ponds and rivers, and burrows in their banks, it is, in itself considered, a remarkable fact that he should have voluntarily transferred himself, by means of dams and ponds of his own construction, from a natural to an artificial mode of life.

"Some of these dams are so extensive as to forbid the supposition that they were the exclusive work of a single pair, or of a single family of beavers; but it does not follow, as has very generally been supposed, that several families, or a colony, unite for the joint construction of a dam. After careful examination of some hundreds of these structures, and of the lodges and burrows attached to many of them, I am altogether satisfied that the larger dams were not the joint-product of the labour of large numbers of beavers working together, and brought thus to immediate completion; but, on the contrary, that they arose from small beginnings, and were built upon year after year, until they finally reached that size which exhausted the capabilities of the location; after which they were maintained for centuries, at the ascertained standard, by constant repairs. So far as my observations have enabled me to form an opinion, I think they were usually, if not invariably, commenced by a single pair, or a single family of beavers; and that when, in the course of time, by the gradual increase of the dam, the pond had become sufficiently enlarged to accommodate more families than one, other families took up their residence upon it, and afterwards contributed by their labour to its maintenance. There is no satisfactory evidence that the American beavers either live or work in colonies; and if some such cases have been observed, it will either be found to be an exception to the general rule, or in consequence of the sudden destruction of a work upon the maintenance of which a number of families were at the time depending.

"The great age of the larger dams is shown by their size, by the large amount of solid materials they contain, and by the destruction of the primitive forest within the area of the ponds; and also by the extent of the beaver-meadows along the margins of the streams where dams are maintained, and by the hummocks formed upon them by and through the annual growth and decay of vegetation in separate hills. These meadows were undoubtedly covered with trees adapted to a wet soil when the dams were constructed. It must have required long periods of time to destroy every vestige of the ancient forest by the increased saturation of the earth, accompanied with occasional overflows from the streams. The evidence from these and other sources tends to show that these dams have existed in the same places for hundreds and thousands of years, and that they have been maintained by a system of continuous repairs.

"At the place selected for the construction of a dam, the ground is usually firm and often stony, and when across the channel of a flowing stream, a hard rather than a soft bottom is preferred. Such places are necessarily unfavourable for the insertion of stakes in the ground, if such were, in fact, their practice in building dams. The theory upon which beaver-dams are constructed is perfectly simple, and involves no such necessity. Soft earth, intermixed with vegetable fibre, is used to form an embankment, with sticks, brush, and poles embedded within these materials to bind them together, and to impart to them the requisite solidity to resist the effects both of pressure and of saturation. Small sticks and brush are used, in the first instance, with mud and earth and stones for down-weight. Consequently these dams are extremely rude at their commencement, and they do not attain their remarkably artistic appearance until after they have been raised to a considerable height, and have been maintained, by a system of annual repairs, for a number of years."[108]

[108] L. H. Morgan, The American Beaver and his Works, Philadelphia, 1868, pp. 82-86.

There are two different kinds of beaver-dams, although they are both constructed on the same principle. One, the stick-dam, consists of interlaced stick and pole work below, with an embankment of earth raised with the same material upon the upper or water face. This is usually found in brooks or large streams with ill-defined banks. The other, the solid-bank dam, is not so common nor so interesting, and is usually found on those parts of the same stream where the banks are well defined, the channel deep, and the current uniform. In this kind the earth and mud entirely buries the sticks and poles, giving the whole a solid appearance. In the first kind the surplus water percolates through the dam along its entire length, while in the second it is discharged through a single opening in the crest formed for that purpose.

The materials being prepared in the manner I have previously described, the animals make ready to establish their dyke. They intermix their materials—driftwood, green willows, birch, poplars, etc.—in the bed of the river, with mud and stones, so making a solid bank, capable of resisting a great force of water; sometimes the trees will shoot up forming a hedge. The dam has a thickness of from three to four metres at the base, and about sixty centimetres at the upper part. The wall facing up-stream is sloping, that directed down-stream is vertical; this is the best arrangement for supporting the pressure of the mass of water which is thus expended on an inclined surface. In certain cases Beavers carry hydraulic science still further. If the course of the water is not very rapid, they generally make an almost straight dyke, perpendicular to the two banks, as this is then sufficient; but if the current is strong, they curve it so that the convexity is turned up-stream. In this way it is much better fitted to resist. Thus they do not always act in the same way, but arrange their actions so as to adapt them to the conditions of the environment.

The embankment being completed, the animals construct their lodges. Fragments of wood, deprived of the bark, are arranged and united by clay or mud which the Beavers take from the riverside, transport, mix, and work with their fore-paws. During a single night they can collect as much mud at their houses as amounts to some thousands of their small handfuls. They thus plaster their houses with mud every autumn; in the winter this freezes as hard as a stone and protects them from enemies. These cabins form domes from three to four metres in diameter at the base, and from two to two and a half metres in height. The floor is on a level with the surface of the artificial pond. A passage sinks in the earth and opens about one and a half metres below the level of the water, so that it cannot be closed up by ice during the severe winters of these regions.

Within, near the entry, the beavers form, with the aid of a partition, a special compartment to serve as a storehouse, and they there pile up enormous heaps of nenuphar roots as provisions for the days when ice and snow will prevent them from barking the young trunks.

A dwelling of this kind may last for three or four years, and the animal here tranquilly enjoys the fruits of its industry, as long as man fails to discover the retreat; for the beaver can escape by swimming from all carnivorous animals excepting, perhaps, the Otter. During floods the level of the water nearly reaches the hut; if the inundation is prolonged and the animal runs the risk of being asphyxiated beneath his dome, it breaks through the upper part with its teeth and escapes. When the water returns to its bed the beaver comes back, makes the necessary repairs, and resumes the usual peaceful course of its life.[109]

[109] The Beaver has been fully studied by Lewis H. Morgan, The American Beaver, 1868. See also Horace T. Martin's recent work, Castorologia, or the History and Traditions of the Canadian Beaver, 1892; in an appendix to this work will be found Samuel Hearne's classical account of the Beaver, written nearly two hundred years ago, and free from the many exaggerations and superstitions which have grown up around this animal.

We have thus seen, from a shapeless hole to these complex dwellings, every possible stage; we have found among animals the rudiments of the different human habitations, certain animals, indeed, having arrived at a degree of civilisation which Man himself in some countries has not yet surpassed, or even indeed yet attained.



CHAPTER VII.

THE DEFENCE AND SANITATION OF DWELLINGS.

GENERAL PRECAUTIONS AGAINST POSSIBLE DANGER—SEPARATION OF FEMALES WHILE BROODING—HYGIENIC MEASURES OF BEES—PRUDENCE OF BEES—FORTIFICATIONS OF BEES—PRECAUTIONS AGAINST INQUISITIVENESS—LIGHTING UP THE NESTS.

The building of comfortable dwellings is not the last stage reached by the industry of animals. There are among them some who show genuine skill in rendering them healthy and defending them against invasions from without.

General precautions against possible danger.—Some animals show, even during the construction of the nest, extreme prudence in preventing its site from being discovered. Several authors refer to the stratagem of the Magpie, who begins several nests at the same time; but only one is intended to receive the brood, and that only is completed. The aim of the others is merely to distract attention. It is around these latter that the bird shows ostentatious activity, while it works at the real nest only for a few hours during the day, in the morning and evening.

The Crane takes equally ingenious precautions in order that its constant presence at the same spot may not arouse suspicion. It never comes or goes flying, but always on foot, concealing itself along tufts of reeds. De Homeyer even reports that the female at the time of laying covers her wings and back with mud. When dried this gives the animal a red tone, which causes it to be confused with neighbouring objects; this is intentional mimicry.

The Linnet (Fig. 41) again, wrongly accused of wanting judgment, is well aware that a pile of excrement at the foot of a tree announces a nest in the branches. It is careful to suppress this revealing sign, and every day takes it away in its beak to disperse it afar.



Birds will sometimes take the trouble to remove the eggs or the nest altogether, when the latter has been discovered, in order to avoid further risks of danger. The American Sparrow Hawk has been observed to do this, and the following incident is quoted by Bendire, from MacFarlane's Manuscript Notes on Birds Nesting in British America, concerning the Pigeon Hawk (Falco columbarius):—"On May 25, 1864, a trusty Indian in my employ found a nest placed in a thick branch of a pine tree at a height of about six feet from the ground. It was rather loosely constructed of a few dry sticks and a small quantity of coarse hay; it then contained two eggs; both parents were seen, fired at, and missed. On the 31st he revisited the nest, which still held but two eggs, and again missed the birds. Several days later he made another visit thereto, and, to his surprise, the eggs and parents had disappeared. His first impression was that some other person had taken them; but after looking carefully around he perceived both birds at a short distance, and this led him to institute a search which soon resulted in finding that the eggs must have been removed by the parent birds to the face of a muddy bank at least forty yards distant from the original nest. A few decayed leaves had been placed under them, but nothing else in the way of lining. A third egg had been added in the interim. There can hardly be any doubt of the truth of the foregoing facts."[110]

[110] Bendire, Life Histories of North American Birds, 1892, p. 301.

Separation of females while brooding.—The Hornbill of Malacca[111] assures the protection of its nest and of the female while she is brooding in a singular manner. She lays in the hollow of a tree; as soon as she begins to sit on her eggs, the male closes the opening with diluted clay, only leaving a hole through which the captive can pass her beak to receive the fruits which he brings her in abundance. If the lady is thus cloistered as closely as in the most jealous harem, her lord and master at least expends on her the most attentive cares.

[111] Bernstein, "Ueber Nester und Eier einiger Javaschen Voegel," Cabani's Journ. f. Ornith., 1859.

What can be the object of this strange custom? It has been asserted that during incubation the female loses her feathers and becomes unable to fly. The male would thus only wall her up as a precaution for fear of seeing her fall from the nest; because if this deplorable accident happened she would not be able to get back again. It seems to me that the effect is here taken for the cause, and that the falling off of feathers and torpidity must be the result rather than the motive of cloistration. One is tempted to believe that the male desires by this method to guarantee his female and her offspring against the attacks of squirrels or rapacious birds.

Hygienic measures of Bees.—Among the animals who expend industry on hygiene and the protection of their dwellings, we must place Bees in the first line. It may happen that mice, snakes, and moths may find their way into a hive. Assaulted by the swarm, and riddled with stings, they die without being able to escape. These great corpses cannot be dragged out by the Hymenoptera, and their putrefaction threatens to cause disease. To remedy this scourge the insects immediately cover them with propolis—that is to say, the paste which they manufacture from the resin of poplars, birches, and pines. The corpse thus sheltered from contact with the air does not putrefy. In other respects Bees are very careful about the cleanliness of their dwellings; they remove with care and throw outside dust, mud, and sawdust which may be found there. Bees are careful also not to defile their hives with excrement, as Kirby noted; they go aside to expel their excretions, and in winter, when prevented by extreme cold or the closing of the hive from going out for this purpose, their bodies become so swollen from retention of faeces that when at last able to go out they fall to the ground and perish. Buechner records the observations of a friend of his during a season in which a severe epidemic of dysentery had broken out among the bees, which interfered with the usual habits of the insects; on careful examination of a hive it was found that a cavity in the posterior wall of the hive, containing crumbled clay, had been used as an earth closet. Many mammals are equally careful in this respect; thus, for example, the Beaver, as Hearne observed, always enters the water, or goes out on the ice, to urinate or defaecate; the faeces float and are soon disintegrated.

Animals are also careful about aeration. Thus, among Bees, in a hive full of very active insects the heat rises considerably and the air is vitiated. A service for aeration is organised. Bees ranged in files one above the other in the interior agitate their wings with a feverish movement; this movement causes a current of air which can be felt by holding the hand before the opening of the hive. When the workers of the corps are fatigued, comrades who have been resting come to take their place. These acts are not the result of a stupid instinct which the Hymenoptera obey without understanding. If we place a swarm, as Huber did, in a roomy position where there is plenty of air, they do not devote themselves to an aimless exercise. This only takes place in the narrow dwellings which Man grants to his winged guests.

The attention of Ants to public hygiene is more than equalled by their attention to personal hygiene. Without going into the question of their athletic exercises, which have attracted considerable attention, it is sufficient to quote one observer as to their habits of cleanliness. McCook remarks:—"The Agricultural Ants—and the remark applies to all other Ants of which I have knowledge—is one of the neatest of creatures in her personal habits. I think I have never seen one of my imprisoned harvesters, either Barbatus or Crudelis, in an untidy condition. They issue from their burrows, after the most active digging, even when the earth is damp, without being perceptibly soiled. Such minute particles of dust as cling to the body are carefully removed. Indeed, the whole body is frequently and thoroughly cleansed, a duty which is habitually, I might almost venture to say invariably, attended to after eating and after sleep. In this process the Ants assist one another; and it is an exceedingly interesting sight which is presented to the observer when this general 'washing up' is in progress."[112]

[112] H. C. McCook, Agricultural Ants of Texas, 1879, chapter on "Toilet, Sleeping, and Funeral Habits," p. 125.

Prudence of Bees.—Certain species exhibit very great prudence, especially the Melipona geniculata, which lives in a wild state in South America. They place their combs in the hollow of a tree or the cleft of a rock; they fill up all the crevices and only leave a round hole for entry. And even this they are accustomed to close every evening by a small partition, which they remove in the morning. This door is shut with various materials, such as resin or even clay, which the bees bring on their legs as those of our own country bring pollen.

All these facts were observed with great exactness in a swarm given in 1874 by M. Drory (who during a long period of years studied every Brazilian species of Melipona at Bordeaux) to the Jardin d'Acclimatation. It was even seen that the door might be put up under certain circumstances in open day, as for example, when a storm or sudden cold delays the appearance of the workers. If one of them happened to be late it had to perforate the partition, and the hole was then stopped up again.



Fortifications of Bees.—As these facts take place always they may be called instinctive; but that is not the case with regard to defences elevated with a view to a particular circumstance, and which disappear when the danger to which they correspond disappears. Such are the labours of the bees to repel the invasions of the large nocturnal Death's-head Moth. (Fig. 42.) He is very greedy of honey, and furtively introduces himself into the hives. Protected by the long and fluffy hairs which cover him, he has little to fear from stings, and gorges himself with the greatest freedom on the stores of the swarm. Huber, in his admirable investigations,[113] narrates that one year in Switzerland numbers of hives were emptied, and contained no more honey in summer than in the spring. During that year Death's-head Moths were very numerous. The illustrious naturalist soon became certain that this moth was guilty of the thefts in question. While he was reflecting as to what should be done, the bees, who were more directly interested, had invented several different methods of procedure. Some closed the entrance with wax, leaving only a narrow opening through which the great robber could not penetrate. Others built up before the opening a series of parallel walls, leaving between them a zigzag corridor through which the Hymenoptera themselves were able to enter. But the intruder was much too long to perform this exercise successfully. Man utilises defences of this kind; it is thus at the entrance of a field, for example, he places a turnstile, or parallel bars that do not face each other; the passage is not closed for him, but a cow is too long to overcome the obstacle. In years when the Death's-head Moth is rare the bees do not set up these barricades, which, indeed, they themselves find troublesome. For two or three consecutive years they leave their doors wide open. Then another invasion occurs, and they immediately close the openings. It cannot be denied that in these cases their acts agree with circumstances that are not habitual.[114]

[113] Huber, Nouvelles observations sur les Abeilles.

[114] These facts have recently been observed and recorded afresh by Mr. Clifford in Nature Notes, January 1893.

Precautions against inquisitiveness.—I will finally quote a fact of defence which took place under circumstances that were absolutely exceptional, and which therefore exhibits genuine reflection in these insects. During the first exhibition of 1855 an artificial hive was set up, one face of which was closed by a glass pane. A wooden shutter concealed this pane, but passers-by opened it every moment to contemplate the work of the small insects. Annoyed by this inquisitiveness, the bees resolved to put an end to it, and cemented the shutter with propolis. When this substance dried it was no longer possible to open the shutter. The bees were visible to nobody.



Lighting up the nests.—An improvement of another nature in the comfort of the dwelling is introduced by the Baya, and if the facts narrated are correct they are the most marvellous of all. It is a question of lighting up a nest by means of Glow-worms. The Melicourvis baya inhabits India; it is a small bird related to the Loxia, already spoken of in this book. Like the latter it constructs a nest that is very well designed and executed. (Fig. 43.) It suspends it in general from a palm tree, but sometimes also from the roofs of houses. In these shelters, woven with extreme art, are always to be found little balls of dry and hardened clay. Why does the bird amass these objects? Is it impelled by a collector's instinct less perfect than that of the Bower-bird? There is no reason to suppose this. Nor does it appear that he wishes to make the nest heavier and prevent it by this ballast from being blown about by every breeze when the couple are out, and the young not heavy enough to ensure the stability of the edifice. The part played by these little balls is much more remarkable, if we may trust the evidence of the natives, as confirmed by competent European observers. Thus Mr. H. A. Severn writes:—"I have been informed on safe authority that the Indian Bottle-bird protects his nest at night by sticking several of these glow-beetles around the entrance by means of clay; and only a few days back an intimate friend of my own was watching three rats on a roof-rafter of his bungalow when a glow-fly lodged very close to them; the rats immediately scampered off."[115] These observations are confirmed by Captain Briant, as reported by Professor R. Dubois.[116] In tropical regions luminous insects give out a brilliant light, of which the Glow-worms of northern countries can only give a feeble idea. These flying or climbing stars are the constellations of virgin forests. In South America the Indians utilise one of these insects, the Cucujo, by fastening it to the great toe like a little lantern, and profit by its light to find their road or to preserve their naked feet from snakes. The first missionaries to the Antilles, lacking oil for their lamps, sometimes replaced them by Fire-flies to read matins by.[117] The Melicourvis baya had already discovered this method of lighting, and the mysterious little balls of clay were nothing more than candlesticks in which these birds set Glow-worms, when they are fresh, to act as candles. The entrance to the nest is thus luminous. (Fig. 44.) Apparently this lighting up is a defensive measure, for the birds have nothing to do at night except to sleep, and must be rather incommoded than cheered by this light. But the terrible enemy of all broods, the Snake, is, it is said, frightened by this illumination, which is able to penetrate the meshes of the nest, and will not dare to enter. The system is ingenious, and the Roman Emperors, when they used burning Christians as torches, were only plagiarising from this little bird, which paves with martyrs the threshold of its house of love.

[115] "Notes on the Indian Glow-fly," Nature, 23rd June 1881.

[116] Science et Nature, t. iv. (1885), No. 94, p. 232.

[117] P. Dutertre, Hist. des Antilles francaise, 1667.



CHAPTER VIII.

CONCLUSION.

DEGREE OF PERFECTION IN INDUSTRY INDEPENDENT OF ZOOLOGICAL SUPERIORITY—MENTAL FACULTIES OF THE LOWER ANIMALS OF LIKE NATURE TO MAN'S.

Degree of perfection in industry independent of zoological superiority.—As the result of our study we see the fundamental industries of Man dispersed throughout the animal kingdom, though not, indeed, all of them, nor the more subtle, which were only born yesterday. We may remark the extent to which intellectual manifestations of this sort are independent of the more or less elevated rank assigned to species in zoological classification. The latter, as it should be, brings together or separates beings according to their physical character. But intelligence does not depend on the whole body; its superior or inferior development is related to a certain corresponding complexity in the surface, volume, and histologic structure of the nervous centres.

It happens with the cerebral as with the other functions. An animal's superiority is not exhibited in all his organs nor in all his qualities; it results from a certain grouping of characters in which there may be weak points. The highest in organisation are not necessarily the swiftest or the strongest, any more than they are necessarily the most intelligent. It may happen; it happens in the case of Man; but it as easily fails to happen. In organisation the Horse is nearer to Man than the Ant; but it is far otherwise as regards intellectual development.

For this reason, when following the progress of any industry, I have taken my examples first in one group, then in another far-removed group, to return afterwards to the first. There are not, and cannot be, bonds between a solitary function of the being and its place in classification—a place which has been determined by the form of all the organs, without even taking into account their methods of activity.

Comparative anatomy has long since removed the barriers, once thought impassable, raised by human pride between Man and the other animals. Our bodies do not differ from theirs; and moreover, such glimpses as we are able to obtain allow us to conclude that their psychic faculties are of the same nature as our own. Man in his evolution introduces no new factor.

The industries in which the talents of animals are exercised demonstrate that, under the influence of the same environment, animals have reacted in the same manner as Man, and have formed the same combinations to protect themselves from cold or heat, to defend themselves against the attacks of enemies, and to ensure sufficient provision of food during those hard seasons of the year when the earth does not yield in abundance.

It must only be added, to avoid falling into exaggeration, that Man excels in all the arts, of which only scattered rudiments are found among the other animals; and we may safeguard our pride by affirming that we need not fear comparison. If our intelligence is not essentially different from that of animals, we have the satisfaction of knowing that it is much superior to theirs.



APPENDIX.

BIBLIOGRAPHY.

Brehm's Thierleben is the great repository of facts concerning the social lives of the higher animals. The third edition, in ten large volumes, fully illustrated, and edited by Pechuel Loesche, has lately appeared (Leipzig und Wien, Bibliog. Institute, 1890-92). It is, indeed, as Virchow has lately termed it, "a sort of zoological library," popular in character, and almost purely descriptive. (There is a French edition of this work in nine volumes, but, with the exception of one fragment, it has not appeared in English. The nearest approach to Brehm's work in England is Cassell's New Natural History, and in America the Riverside Natural History.) It is impossible to enumerate the numberless works by travellers and others on which the knowledge of animal industries is founded. The works of Huber, Fabre, Audubon, Le Vaillant, C. St. John, Belt, Bates, Tennent, are frequently quoted in the course of this work. Many of the most important and detailed studies of animal industries are scattered through the pages of the scientific periodicals of all countries. References to a few of the chief of these studies will be found in the text.

For a scientific discussion of the phenomena of animal skill and intelligence we may perhaps best turn to Professor C. Lloyd Morgan, whose work is always both acute and cautious. In Animal Life and Intelligence (1890) he has furnished an excellent introduction to the subject. In his Introduction to Comparative Psychology (shortly to appear in the Contemporary Science Series) he discusses the fundamental problems of mental processes in animals, and the transition from animal intelligence to human intelligence. Romanes' Mental Evolution in Animals (1883) and other works by this writer, dealing with the same subject, but proceeding on a different method, should also be studied; and his Animal Intelligence (International Science Series) is an excellent critical summary of the facts. Buechner's Aus dem Geistesleben der Thiere (Berlin, 1877) and Houzeau's Facultes Mentales des Animaux (Brussels, 1877) may also be mentioned, and Espinas' Societes Animales (1877), though dealing primarily with sociology, is an original and suggestive study of great value.

As a general introduction, of a popular but not unscientific character, to all the various aspects of animal life, J. Arthur Thomson's little book, The Study of Animal Life (University Extension Manuals, 1892), may be recommended. At the end of Mr. Thomson's volume will be found a useful classified list of the "Best Books" on animal life.

GARDENING ANTS.

The operations of various species of Gardening Ants have recently been very thoroughly investigated at Blumenau by Herr Alfred Moeller, nephew of Dr. Fritz Mueller ("Die Pilzgaerten einiger suedamerikanischer Ameisen." Heft 6 of Schimper's "Botanische Mittheilungen aus den Tropen." Jena: G. Fischer, 1893. Herr Moeller's work is clearly summarised by Mr. John C. Willis in "The Fungus Gardens of certain South American Ants," Nature, 24th August 1893).

The ants of Blumenau chiefly differ from those described by Belt in that they form very narrow streets, in which they travel only in single file, and also that their nests occur both in the forest and in the open. The commonest species is the Atta (Acromyrmex) discigera, Mayr, and the workers are never more than 6.5 mm. long. There are other species of Atta which have very similar streets; one, the Atta hystrix, Latr., appears to work only at night. A minute description is given of a street of A. discigera, which was 26 metres long and about 1.5 cm. wide and high, roofed in in parts wherever possible. It led to a number of small Cupheas, whose leaves the ants were cutting. In the street could be seen a procession of loaded ants going towards the nest, and others empty-handed, going in the opposite direction. Some of the large workers run up and down the road unloaded, and act as road-menders if any accident happens to a part of the track. Other very small workers, which do not cut leaves, may also be seen carried upon the backs or even upon the loads of the actual leaf-cutters. An ant carrying a peculiarly shaped piece of leaf was watched from end to end of the track, and travelled the 26 m. in 70 minutes. The load was twice as heavy as itself.