Chapter XI: Front Matter (11)

The badger’s dwelling appears to the fox particularly enviable. In order to dislodge the proprietor he adopts the following plan: Knowing that the latter can tolerate no ordure near his home, he chooses as a place of retirement one of the passages which lead to the chamber of the peaceful recluse. He insists repeatedly, until at last the badger, insulted by this grossness, and suffocated by the odor, decides to move elsewhere and hollow a fresh palace. The fox is only waiting for this, and installs himself.

The vizcacha (Lagostomus trichodactylus) is a large rodent inhabiting a vast extent of country in the pampas of La Plata, Patagonia, etc. Unlike most other burrowing species, the vizcacha prefers to work on open level spots. On the great grassy plains it is even able to make its own conditions, like the beaver, and is in this respect, and in its highly developed social instinct, among the two or three mammals which approach man, although only a rodent, and even in this order, according to Waterhouse, coming very low down by reason of its marsupial affinities.

The vizcacha lives in small communities of from twenty to thirty members, in a village of deep-chambered burrows, some twelve or fifteen in number, with large pit-like entrances closely grouped together, and as the vizcachera, as this village is called, endures for an indefinitely long period, the earth which is constantly brought up forms an irregular mound thirty or forty feet in diameter, and from fifteen to thirty inches above the level of the road; this mound serves to protect the dwelling from floods on low ground. A clearing is made all round the abode and all rubbish thrown on the mound; the vizcachas thus have a smooth turf on which to disport themselves, and are freed from the danger of lurking enemies.

The entire village occupies an area of one hundred to two hundred square feet of ground. The burrows vary greatly in extent; usually in a vizcachera there are several that, at a distance of from four to six feet from the entrance, open into large circular chambers. From these chambers other burrows diverge in all directions, some running horizontally, others obliquely downward to a maximum depth of six feet from the surface; some of these galleries communicate with those of other burrows.

On viewing a vizcachera closely, the first thing that strikes the observer is the enormous size of the entrances to the central burrows in the mound; there are usually several smaller outside burrows. The entrance to some of the principal burrows is sometimes four to six feet across the mouth, and sometimes it is deep enough for a tall man to stand in up to the waist.

Certain rodents have carried hollow dwellings to great perfection. Among these the hamster of Germany (Cricteus frumentarius) is not the least ingenious. To his dwelling-room he adds three or four storehouses for amassed provisions. The burrow possesses two openings: one, which the animal prefers to use, which sinks vertically into the soil; the other, the passage of exit, with a gentle and very winding slope. The bottom of the central room is carpeted with moss and straw, which make it a warm and pleasant home. A third tunnel starts from this sleeping chamber, soon forking and leading to the wheat barns. Thus during the winter the hamster has no pressing need to go out except on fine days for a little fresh air. He has everything within his reach, and can remain shut up with nothing to fear from the severity of the season.

It is not only the soil which may serve for retreat; wood serves as an asylum for numerous animals, who bore it, and find in it both food and shelter. In this class must be placed a large number of worms, insects, and crustaceans. One of these last, the Chelura terebrans, a little amphipod, constitutes a great danger for the works of man. It attacks piles sunken to support structures, and undermines them to such a degree that they eventually fall.

An insect, the Xylocopa violacea, related to the humblebee, from which it differs in several anatomical characters, and by the dark violet tint of its wings, brings an improvement to the formation of the shelter which it makes in wood for its larvæ. Instead of hollowing a mere retreat to place there all its eggs indiscriminately, it divides them into compartments, separated by horizontal partitions. It is the female alone who accomplishes this task, connected with the function of perpetuating the race. She chooses an old tree-trunk, a pole, or the post of a fence, exposed to the sun and already worm-eaten, so that her labor may be lightened. She first attacks the wood perpendicularly to the surface, then suddenly turns and directs downward the passage, the diameter of which is about equal to the size of the insect’s body. The Xylocopa thus forms a tube about thirty centimetres in length. Quite at the bottom she places the first egg, leaving beside it a provision of honey necessary to nourish the larva during its evolution; she then closes it with a partition. This partition is made with fragments of the powder of wood glued together with saliva. A first horizontal ring is applied round the circumference of the tube; then in the interior of this first ring a second is formed, and so on continuously, until the central opening, more and more reduced, is at last entirely closed up. This ceiling forms the floor for the next chamber, in which the female deposits a new egg, provided, like the other, with abundant provisions. The same acts are repeated until the retreat becomes transformed into a series of isolated cells in which the larvæ can effect their development, and from which they will emerge either by themselves perforating a thin wall which separates them from daylight, or by an opening which the careful mother has left to allow them to attain liberty without trouble.

The second class of habitation, which I have called the woven dwelling, proceeds at first from the parceling up of substances, then of objects capable of being entangled like wisps of wood or straw, then of fine and supple materials which the artisan can work together in a regular manner, that is to say, by felting or weaving.

There are, first, cases in which the will of the animal does not intervene, or at least is very slightly manifested. The creature is found covered and protected by foreign bodies which are often living beings. Spider-crabs (Maïa), for example, have their carapaces covered with algæ and hydroids of all sorts. Thus garnished, the Crustaceans have the advantage of not being recognized from afar when they go hunting, since beneath this fleece they resemble some rock. H. Fol has observed at Villefranche-sur-Mer a Maïa so buried beneath this vegetation that it was impossible at first sight to distinguish it from the stones around. Under these conditions the animal submits to a shelter rather than creates it. Yet it is not so passive as one might at first be led to suppose. When the algæ which flourish on its back become too long and impede or delay its progress, it tears them off with its claws and thoroughly cleans itself. The carapace being quite clean, the animal finds itself too smooth and too easy to distinguish from surrounding objects; it therefore takes up again fragments of algæ and replaces them where they do not delay to take root like cuttings and to flourish anew.

The sponge-crab (Dromia vulgaris) also practices this method of shelter. It seizes a large sponge and maintains it firmly over its carapace with the help of the posterior pair of limbs. The sponge continues to prosper and to spread over the Crustacean who has adopted it. The two beings do not seem to be definitely fixed to each other; the contact of a sudden wave will separate them. When the divorce is effected, the Dromia immediately throws itself on its cherished covering and replaces it. M. Künckel d’Herculais tells of one of these curious Crustaceans which delighted the workers in the laboratory of Concarneau. The need for covering themselves experienced by these crabs is so strong that in aquariums when their sponge is taken away they will apply to the back a fragment of wrack or of anything which comes to hand. A little white cloak with the arms of Brittany was manufactured for one of these captives, and it was very amusing to see him put on his overcoat when he had nothing else wherewith to cover himself.

An Australian bird, the Catheturus Lathami, as described by Gould, is still in the rudiments, and limits itself to preparing an enormous pile of leaves. It begins its work some weeks before laying its eggs; with its claws it pushes behind it all the dead leaves which fall on the earth and brings them into a heap. The bird throws new material on the summit until the whole is of suitable height. This detritus ferments when left to itself, and a gentle heat is developed in the centre of the edifice. The Catheturus returns to lay near this coarse shelter; it then takes each egg and buries it in the heap, the larger end uppermost. It places a new layer above, and quits its labor for good. Incubation takes place favored by the uniform heat of this decomposing mass, hatching is produced, and the young emerge from their primitive nest.

Birds are not alone in constructing temporary dwellings in which to lay their eggs; some fish are equally artistic in this kind of industry, and even certain reptiles. The alligator of the Mississippi would not perhaps at first be regarded as a model of maternal foresight. Yet the female constructs a genuine nest. She seeks a very inaccessible spot in the midst of brushwood and thickets of reeds. With her jaw she carries thither boughs which she arranges on the soil and covers with leaves. She lays her eggs and conceals them with care beneath vegetable remains. Not yet considering her work completed, she stays in the neighborhood watching with jealous eye the thicket which shelters the dear deposit, and never ceases to mount guard threateningly until the day when her young ones can follow her into the stream.

A hymenopterous relative of the bees, the Megachile, cuts out in rose-leaves fragments of appropriate form which it bears away to a small hole in a tree, an abandoned mouse nest or some similar cavity. There it rolls them, works them up, and arranges them with much art, so as to manufacture what resemble thimbles, which it fills with honey and in which it lays.

The Anthocopa acts in a similar manner, carpeting the holes of which it takes possession with the delicate petals of the corn poppy.

The retreats of nocturnal birds of prey do not differ in method of construction from these two kinds of nests. They are holes in trees, in ruins, in old walls, and are lined with soft and warm material. These dwellings are related, not to the type of the hollowed cave, but to that of the habitation manufactured from mingled materials. They constitute an inferior form in which the pieces are not firmly bound together, but need support throughout. The cavity is the support which sustains the real house.

Diurnal birds of prey are the first animals who practice skilfully the twining of materials. Their nests, which have received the name of eyries, are not yet masterpieces of architecture, and reveal the beginning of the industry which is pushed so far by other birds. Usually situated in wild and inaccessible spots, the young are there in safety when their parents are away on distant expeditions. The abrupt summits of cliffs and the tops of the highest forest trees are the favorite spots chosen by the great birds of prey. The eyrie generally consists of a mass of dry branches which cross and mutually support one another, constituting a whole which is fairly resistant.

The abodes of squirrels, though exhibiting more art, are constructions of the same nature; that is to say, they are formed of interlaced sticks. This animal builds its home to shelter itself there in the bad season, to pass the night in, and to rear its young. Very agile, and not afraid of climbing, it places its domicile near the tops of our highest forest trees. Rather capricious also, and desiring change of residence from time to time, it builds several of them; at least three or four, sometimes more. The materials which it needs are collected on the earth among fallen dead branches, or are torn away from the old abandoned nest of a crow or some other bird. The squirrel first builds a rather hollow floor by intermingling the fragments of wood which it has brought. In this state its dwelling resembles a magpie’s nest. But the fastidious little animal wishes to be better protected and not thus to sleep in the open air. Over this foundation he raises a conical roof; the sticks which form it are very skilfully disposed, and so well interlaced that the whole is impenetrable to rain. The house must still be furnished, and this is done with Oriental luxury; that is to say, the entire furniture consists of a carpet, a carpet of very dry moss, which the squirrel tears from the trunks of trees, and which it piles up so as to have a soft and warm couch. An entrance situated at the lower part gives access to the aerial castle; it is usually directed toward the east. On the opposite side there is another orifice by which the animal can escape if an enemy should invade the principal entrance. In ordinary times also it serves to ventilate the chamber by setting up a slight current of air. The squirrel greatly fears storms and rain, and during bad weather hastens to take refuge in his dwelling. If the wind blows in the direction of the openings, the little beast at once closes them with two stoppers of moss, and keeps well shut in as long as the storm rages.

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 neighboring boughs, crosses them, and interlaces them so as to obtain a sort of framework. When this preliminary labor 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.

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 midday sun as well as against tropical showers.

There exists in Australia 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 arbors in our old gardens, are places for reunion 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 neighborhood 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 arbor 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 toward 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 neighboring stream, shells, the bright feathers of the paroquet, 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 colors of which rejoice the eye. The prettiest treasures are fixed into the wall of the hut. 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.

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.”

In spite of their lack of skill and the inadequacy of their organs, 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.

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 can not 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 (Ægithalus 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 with in England, is always suspended above the water, two or three metres above the surface, fixed to a willow branch. 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. 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 possesses 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 utilized as a rigid frame on which to weave the lateral walls of the habitation. It intercrosses wool and goats’ hair so as to form two courses which are afterward 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.

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. The yellow weaver bird of Java, as described by Forbes, constructs very similar retort-shaped nests.

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 neighboring 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. 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 can not 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.

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 amid 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 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.

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. These labors 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. It is impossible not to admire animals who have skilfully triumphed over all the obstacles met with in the course of these complicated operations.

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 can not well be called anything else but sewing it.

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 gray sphere prolonged to a blunt neck. The hornet’s nest is similar in construction.

Gelatine nests 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. 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.

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 toward the bottom, and making an external prominence. The owner comes and goes by this passage, and as it is curved toward 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 endeavor to penetrate into their nests and lay their eggs there. The gallery of entry and exit has been built with grains of sand, the débris produced by the insect in working. These grains of sand glued together form, on drying, a very resistant wall.

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 utilized, and to have an inclosed 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.

Besides the swallows, birds offer us several types of skilful construction with tempered earth.

The flamingo, which lives in marshes, can not 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 makes a dwelling of dried earth in 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 labors a large horizontal branch, it brings to it a number of little clay balls more or less combined with vegetable débris, works them all together, 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 outward. This becomes hard; it raises it by a new application, this time inclined inward. All the other layers which will be placed above this will also be inclined toward 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 can not 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.

The muskrats 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 sixty-five 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.

1, Caraphractus Cinctus, Male; 2, 3, same, Female; 4, 5, Mymar Pulchellus, Male and Female; 6, 7, Prestwichia Aquatica, Female and Male; 8, Cosmocomo Fumipennis, Female]

But it is, above all, the beaver (Castor fibre) 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.

The civilization of the beaver has perished in the presence of man’s civilization, 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 dikes; 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 utilize the wood in construction, have chosen a site, and have decided to establish a village on the edge of the water, there are several labors 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 cm. in diameter 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 hindquarters, 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 toward the water. The austerity of labor alternates, it may be added, with the pleasures of the table. From time to time the beavers remove the bark of the fallen trees and feed on it.

Mr. Lewis H. Morgan studied the American beaver with great care and thoroughness, more especially on the southwest 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 labor. 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 labor 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 afterward contributed by their labor 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 unfavorable 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 imbedded 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.”[12]

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 dike. 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 dike, 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 river-side, transport, mix, and work with their forepaws. 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 can not 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 the 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.

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 civilization which man himself in some countries has not yet surpassed, or even indeed yet attained.

MAN’S FIRST APPEARANCE
--BOYD DAWKINS

The characteristics of the evolution of living forms may be summed up as follows:

I. Eocene--in which the placental mammals now on earth were represented by allied forms belonging to existing orders and families. Living orders and families appear; lemurs (Lemuridæ) in Europe and North America. Evidence found in fresh-water and marine strata; lignites.

II. Miocene--in which the alliance between living and placental mammals is more close than before. Living genera appear; apes (Simiadæ) in Europe and North America. Evidence--fresh-water and marine strata; volcanic débris (Auvergne); lignites.

III. Pliocene--in which living species of placental mammals appear. Living species appear; apes (Simiadæ) in Southern Europe. Evidence found in fresh-water and marine strata; volcanic débris (Auvergne).

IV. Pleistocene--in which living species of placental mammals are more abundant than the extinct. Man appears; Anthropidæ; the palæolithic hunter; living species abundant. Evidence--refuse-heaps, contents of caves, river deposits, submarine forests, bowlder clay, moraines, marine sands, and shingle.

V. Prehistoric--in which domestic animals and cultured fruits appear. Man abundant, domestic animals, cultivated fruits, spinning, weaving, pottery-making, mining, commerce; the neolithic, bronze, and iron stages of culture. Evidence--camps, habitations, tombs, refuse-heaps, surface accumulation, caves, alluvia, peat bogs, submarine forests, raised beaches.

VI. Historic--in which the events are recorded in history. Evidence--documents, refuse-heaps, caves, tombs.

The orders, families, genera, and species in the above summary, when traced forward in time, fall into the shape of a genealogical tree, with its trunk hidden in the secondary period, and its branchlets (the living species) passing upward from the Pliocene, a tree of life with living Mammalia for its fruits and foliage. Were the extinct species taken into account, it would be seen that they fill up the intervals separating one living form from another, and that they too grow more and more like the living forms as they approach nearer to the present day. It must be remembered that in the above definitions the fossil marsupials are purposely ignored, because they began their specialization in the secondary period, and had arrived in the Eocene at the stage which is marked by the presence of living genus--the opossum (Didelphys).

It will be seen that our inquiry into the antiquity of man is limited to the last four of the divisions. The most specialized of all animals can not be looked for until the higher Mammalia by which he is surrounded were alive. We can not imagine him in the Eocene age, at a time when animal life was not sufficiently differentiated to present us with any living genera of placental mammals. Nor is there any probability of his having appeared on the earth in the Miocene, because of the absence of higher placental mammals belonging to living species. It is most unlikely that man should have belonged to a fauna in which no other living species of mammal was present. He belongs to a more advanced stage of evolution than the mid-Miocene of Thenay. Up to this time the evolution of the animal kingdom had advanced no further than the Simiadæ in the direction of man; and the apes then haunting the forests of Italy, France, and Germany represent the highest type of those on earth.

We may also look at the question from another point of view. If man were upon the earth in the Miocene age, it is incredible that he should not have become something else in the long lapse of ages, and during the changes in the condition of life, by which all the Miocene land Mammalia have been so profoundly affected that they have been either exterminated or have assumed new forms. Nor in the succeeding Pliocene age can we expect to find man upon the earth, because of the very few living species of placental mammals then alive. It is not until we arrive at the succeeding stage, or the Pleistocene, when living species of Mammalia began to abound, that we meet with indisputable traces of the presence of man on the earth. The rudely chipped implements of the River-drift hunter lie scattered through the late Pleistocene river deposits in southern and eastern England in enormous abundance, and as a rule in association with the remains of animals of Arctic and of warm habit, as well as some one or other of the extinct species of reindeer and hippopotamus along with mammoth and woolly rhinoceros.