spiders, equally curious on account of the various organs by means of which they spin their webs, and of the peculiar and varied instincts by which they are guided in using them. Kirby, in his learned "Bridgewater Treatise," gives the following interesting instances of these instinctive contrivances, taken from this singular class of animals :-" The common black and white spider, which may always be seen in summer on sunny rails, &c., when it spies a fly at a distance, approaches softly, step by step, and seems to measure his distance from it by the eye; then, if he judges that he is within reach, first fixing a thread to the spot on which he is stationed, by means of his fore-feet, which are much larger and stronger than the others, he darts on his victim with such rapidity, and so true an aim, that he seldom misses it. He is prevented from falling by the thread just mentioned, which acts as a kind of anchor, and enables him to recover his station." Again: the kind of spider which has received the name of geometric, “having laid the foundation of her net, and drawn the skeleton of it by spinning a number of rays converging to a centre, next proceeds, setting out from that point, to spin a spiral line of inadhesive web, like that of the rays which it intersects, and, after numerous circumvolutions, finishes this at the circumference. This line, in conjunction with the rays, serves as a scaffolding for her to walk over, and always keeps the rays properly stretched. Her next labour is to spin a spiral line, from the circumference towards the centre, but stopping somewhat short of it; this line is the most important part of the snare. It consists of a fine thread, studded with minute viscid globules, like dew, which, by their viscid quality, retain the insects which fly into the net. The snare being thus finished, the little geometrician selects a concealed spot in the vicinity, where she constructs a cell, in which she may hide herself and watch for game, of the capture of which she is informed by the vibrations of a line of communication, drawn between her cell and the centre of her snare."

I shall now give a few examples of the instinct which urges many animals to form habitations of various kinds, for protection against injury and against cold. These constructions vary much, from the simple contrivance of the earth-worm, which closes the orifice of its hole with leaves or with straw, up to the elaborate structures of the ant, the bee, and the beaver.

Dr. Rosset gives the following account of the labours of the terebella, in constructing its abode :-" The manoeuvres of the terebella are best observed by taking it out of its tube, and placing it under water upon sand. It is then seen to unfold all the coils of its body, to extend its tentacula in every direction, often to a length exceeding an inch and a half, and to catch by their means small pieces of shell and sand. These it drags towards its head, carrying them behind the scales which project from the anterior and lower part of the head, where they are immediately cemented by the glutinous matter which exudes from that part of the surface. Bending the head alternately from side to side, while it continues to apply the materials of its tube, the terebella has very soon formed a complete collar, which it sedulously employs itself to lengthen at every point of the circumference with an activity and perseverance highly interesting. For the purpose of fixing the different fragments compactly, it passes them into their places with the erected scales, at the same time retracting the body. Hence the fragments, being raised by the scales, often give the tube an imbricated

appearance.

Having formed a tube of half an inch or an inch in length, the terebella proceeds to burrow; for which purpose it directs its head against the sand,

and, contracting some of the posterior rings, effects a slight extension of the head, which thus slowly makes its way through the mass before it, availing itself of the materials which it meets with in its course, and so continues to advance, till the whole body is completed. After this has been accomplished, the animal turns itself within the tube, so that its head is next the surface, ready to receive the water which brings it food, and is instrumental in its respiration. In summer, the whole task is completed in four or five hours; but in cold weather, when the worm is more sluggish, and the gluten is secreted more scantily, its progress is considerably slower."*

"The insects that frequent the waters," says Kirby, "require, as well as those which inhabit the earth, predaceous animals to keep them within due limits; and the water-spider is one of the most remarkable on whom that office is imposed by the Creator. To this end, her instinct instructs her to construct a sort of diving-bell, for which purpose she usually selects still waters. Her house is an oval cocoon, filled with air, and lined with silk, from which threads issue in every direction, and are fastened to the surrounding plants; in this cocoon, which is open below, she watches for her prey, and even appears to pass the winter, when she closes the opening. It is most commonly entirely under water; but its inhabitant has filled it with air for respiration, by which she is enabled to live in it. She conveys the air in the following manner: she usually swims upon her back, when her abdomen is enveloped in a bubble of air, and appears like a globe of quicksilver; with this she enters her cocoon, and, displacing an equal mass of water, again ascends for a second lading, till she has sufficiently filled her house with it, so as to expel all the water. The males construct similar habitations by the same manoeuvres. How these little animals can envelope their abdomen with an air-bubble, and retain it till they enter their cells, is still one of nature's mysteries which have not been explained."

The most curious solitary habitations on the earth's surface are also furnished by the tribe of spiders. "Some species of spiders," M. Andouin remarks, are gifted with a particular talent for building: they hollow out dens; they bore galleries; they elevate vaults; they build, as it were, subterranean bridges; they construct also entrances to their habitations, and adapt doors to them, which want nothing but bolts; for, without any exaggeration, they work upon a hinge, and are fitted to a frame. The interior of these habitations is not less remarkable for the extreme neatness which reigns there: whatever be the humidity of the soil in which they are constructed, water never penetrates them; the walls are nicely covered with a tapestry of silk, having usually the lustre of satin, and almost always of a dazzling whiteness.

"The habitations of the species in question are found in an argillaceous kind of red earth, in which they bore tubes about three inches in depth, and ten lines in width. The walls of these tubes are not left just as they are bored, but are covered with a kind of mortar, sufficiently solid to be easily separated from the mass which surrounds it. The door that closes the apartment is still more remarkable in its structure. If the well were always open, the spider would sometimes be subject to the intrusion of dangerous guests. Providence has, therefore, instructed her to construct a very secure trap-door, which closes the mouth of it. To judge of this door by its outward appearance, it appears to be formed of a mass of earth, coarsely worked, and covered internally by a solid web, which would be

"Bridgewater Treatise," vol. i., p. 279.

sufficiently wonderful for an animal which seems to have no special organ for constructing it; but when divided vertically, it is found to be a much more complicated fabric than its outward appearance indicates, it being formed of more than thirty alternate layers of earth and web, emboxed, as it were, in each other, like a set of weights for small scales.

"If these layers of web are examined, it will be seen that they all terminate in the hinge, so that the greater the mass of the door, the more powerful is the hinge. The frame in which the tube terminates above, and to which the door is adapted, is thick, arising from the number of layers of which it consists, and which seem to correspond with those of the door: hence the formation of the door. The hinge and the frame seem to be a simultaneous operation, save that, in fabricating the first, the animal has to knead the earth as well as to spin the layers of web. By this admirable arrangement, these parts always correspond with each other; and the strength of the hinge and the thickness of the frame will always be proportionate to the weight of the door.

"The interior surface of the cover to the tube is not rough and uneven like its exterior, but perfectly smooth and even, like the walls of the tube, being covered with a coating of white silk, but more firm, and resembling parchment, and remarkable for a series of minute orifices placed in the side opposite the hinge, and arranged in a semicircle: there are about thirty of these orifices, the object of which is to enable the animal to hold her door down in any case of emergency, against external force, by the insertion of

her claws into some of them."

As an example of the habitations which are the joint result of the labours of communities, many of which are of the most extraordinary character, I shall give the building of the houses of beavers.

"Beavers," says Kirby, "set about building some time in the month of August those that erect their habitations in small rivers or creeks, in which the water is liable to be drained off, with wonderful sagacity provide against that evil by forming a dike across the stream, almost straight where the current is weak, but where it is more rapid, curving more or less, with the convex side opposed to the stream. They construct these dikes or dams of the same materials as they do their lodges; namely, of pieces of wood of any kind, of stones, mud, and sand. These causeways oppose a sufficient barrier both to water and ice; and, as the willows, poplars, &c., employed in constructing them often strike root in it, it becomes in time a green hedge, in which birds build their nests.

"By means of these erections the water is kept at a sufficient height; for it is absolutely necessary that there should be at least three feet of water above the extremity of the entry into their lodges, without which, in hard frosts, it would be entirely closed. This entry is not on the land side, because it would let in wild animals, but towards the water.

"They begin to excavate under water, at the base of the bank, which they enlarge upwards gradually, and so as to form a declivity, till they reach the surface; and of the earth which comes out of the cavity they form a hillock, with which they mix small pieces of wood, and even stones; they give this hillock the form of a dome, from four to seven feet high, from ten to twelve feet long, and from eight to nine wide. As they proceed in heightening, they hollow it out below, so as to form the lodge which is to receive the family. At the anterior part of this dwelling, they form a gentle declivity, terminating in the water, so that they enter and go out under water.

At a

"The interior forms only a single chamber resembling an oven. small distance is the magazine for provisions. Here they keep in store the roots of the yellow water-lily, and the branches of the black spruce, the aspen, and the birch, which they are careful to plant in the mud. These form their subsistence. Their magazines sometimes contain a cart-load of these articles; and the beavers are so industrious, that they are always adding to their store."*

The nests so admirably constructed by what have been called the perfect societies of insects, the white-ants, or termites; the ants, or formico; the bees, wasps, and humble-bees; are so well known, and have been so often described, that I shall refrain from giving any instances.

Those instincts, relating to what is called the hibernation of animals, are of a very interesting nature, and frequently evidence what in rational beings would be deemed remarkable instances of foresight and prudence. Almost all hibernating animals have instinctive tendencies prompting them to construct for themselves some suitable residence, in which they may be sheltered during winter; and it is very remarkable, that their hiding-places are often formed long before the weather has become very cold. Many hibernating animals exhibit so little of any vital action, as to require little or no nourishment during the winter; but many others, again, are guided by instinct to lay up stores of provisions, on which they subsist during the winter. Some of these (as the lemming) have been observed to spread out their stores to dry in fine weather.

The following curious instance of provision of this kind, I select from Kirby and Spence's "Introduction to Entomology:"

“There is an animal, the rat-hare, which is gifted by the Creator with a very singular instinct, on account of which it ought rather to be called the "hay-maker,' since man may, or might have learned that part of the business of the agriculturalist, which consists in providing a store of winter provender for his cattle, from this industrious animal. Professor Pallas was the first who described the quadruped exercising this remarkable function, and gave an account of it.

"About the middle of August, these little animals collect their winter's provender, formed of select herbs, which they bring near their habitations, and spread out to dry like hay. In September, they form heaps or stacks of the fodder they have collected, under places sheltered from rain or snow. Where many of them have laboured together, their stacks are sometimes as high as a man, and more than eight feet in diameter. A subterranean gallery leads from the burrow below the mass of hay; so that neither frost nor snow can intercept their communication with it. Pallas had the patience to examine their provision of hay piece by piece, and found it to consist chiefly of the choicest grasses and sweetest herbs, all cut when most vigorous, and dried so slowly as to form a green and succulent fodder; he found in it scarcely any ears or blossoms, or hard and woody stems, but some mixture of bitter herbs, probably useful to render the rest more wholesome."

The important instinct of migration is another means by which the lives of many animals are preserved during winter. It has been repeatedly ascertained that the same birds return, after six months' absence and long voyages, to the very spots where they had been brought forth, implying a power of discernment and recollection which appears inconceivable.

*Kirby's "Bridgewater Treatise," vol. ii., p. 510.

I shall now give a few instances of instincts destined for the propagation and support of the offspring. "Several of the crabs," says Kirby," forsake the waters for a time, and return to them to cast their spawn; but the most celebrated of all is that known by the name of land-crab, and alluded to by Dr. Paley, as the violet-crab. They are natives of the West Indies and South America. In the rainy season, in May and June, their instinct impels them to seek the sea, that they may fulfil the great law of the Creator, and cast their spawn. They descend the mountains, which are their usual abode, in such numbers, that the roads and woods are covered with them. They are said to halt twice every day, and to travel chiefly in the night. Arrived at the sea-shore, they are there reported to bathe three or four times, when, retiring to the neighbouring plains or woods, they repose some time; and then the females return to the water, and commit their eggs to the waves. This business despatched, they endeavour to regain, in the same order, the country they had left, and by the same route; but only the most vigorous can reach the mountains."

The object of this migration clearly is, that the female may have an opportunity of depositing her eggs where they will be in circumstances suited to their development, particularly as to the essential requisites, exposure to heat and to air.

The instincts by which animals, particularly birds, are guided in building their nests, are so numerous, varied, and admirably adapted to their purpose, as to have called forth the admiration of all ages.

"I observed," says the Rev. J. Hall, in his "Travels in Scotland,” "two magpies hopping round a large gooseberry-bush, in a small garden, in a peculiar manner, and flying in and out of the bush. I stepped aside to see what they were doing, and found, from the poor man and his wife, that, as there are no trees all around, these magpies several years had built their nest, and brought up their young, in this bush; and, that foxes, cats, hawks, &c., might not interrupt them, they had barricadoed not only their nest, but had encircled the bush with briers and thorns in a formidable manner; nay, so completely, that it would have cost even a fox, cunning as he is, some days' labour to get into the nest.

"The materials in the inside of the nest were soft, warm, and comfortable; but all on the outside so rough, so strong, and so firmly entwined with the bush, that without a hedge-knife, hatch-bill, or something of the kind, even a man could not, without much pain and trouble, get at their young, as from the outside to the inside extended as long as my arm.

"These magpies had been faithful to one another for several summers, and drove off their young, as well as everything else which attempted to take possession of their nest. This they carefully repaired and fortified in the spring, with strong, rough, prickly sticks, which they sometimes brought to it, by uniting their force,-one at each end,-pulling it along when they were not able to lift it from the ground."

The above instance scarcely allows room for doubt that these birds exercised short and simple processes of reasoning, not to be included under what is usually understood by the term "instinct."

Some of the most interesting and wonderful facts pertaining to instinctive manifestations in animals, relate to their power of adapting their operations to changes in their circumstances. I shall give an instance or two of these contrivances :

"The combs of bees," says Kirby, "are always at an uniform distance from one another; namely, about one-third of an inch; which is just wide