fluous threads and coils them into a ball to be thrown away; by this apparatus, she brushes away the dust from her downy body, or cleans her network. From the delicacy of the operations performed by the spider in constructing her meshes, whether of close or open work, one cannot but think that the sense of touch is called into exercise, and that it is seated at least in the clawed joints of the limbs; even in the hunting spiders, which make no webs, and roam about in search of prey, upon which they dart like a tiger, their very mode of capturing their victims would seem to argue the same. We cannot, indeed, doubt that they possess a sense of touch, but to what extent, or how modified, we cannot tell; there is, in fact, something in the senses and instincts of spiders and insects generally beyond our comprehension. They perform labours which astonish us, and they, in many cases, act as if under the guidance of reason, rather than of instinct. In a certain sense, they are highly elevated in the scale of being, while in other respects they are far remote from animals with a brain and well-developed nervous system. In some cases the transfixion of their bodies occasions no symptoms of pain-they will thus eat and live;

but on the other hand who can watch a fly engaged in brushing its wings and back and head, and then rubbing its fore-limbs or hindlimbs together, as if to clean its suckers after being soiled, and not be convinced that it has the sense of touch? We have often been tempted to think that insects may possess senses unappreciable by ourselves, and undescribable because we are not endowed with them. Certainly it is strange that these brainless creatures, with a nervous system so simple, should be so quick, so prompt, so observant, so cautious, so skilful, should display memory and judgment, and be urged by anger or daring, or influenced by apprehension and fear.

Insects are organized for flight, and, besides the ordinary limbs, are furnished with two or four wings, (with certain exceptions,) of a membranous, and often extremely delicate tissue, marked by nervures which are regarded as air-tubes continued from the body. The extent and shape of the wings vary greatly -in some, the wings are smooth, transparent, and glittering; in others, they are covered with scales, or plumes of the most exquisite colours; and in others, as the beetle tribes, they are

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folded up, when at rest, under wing-cases of a more or less rigid consistence. The ordinary limbs are six in number, each divided into five parts, of which the last, or foot, never consists of more than five joints. These parts are the hip, the trochanter, the thigh, the shank, and the foot, or tarsus.

Greatly are these limbs modified in detail in various insects. Some, elevated on long, slender, tremulous limbs, walk over and amidst the blades of grass as if elevated on stilts. Others have them expressly adapted for taking long leaps, as the grass-hoppers, crickets, and treehoppers in some insects, as the fly, they are provided with suckers; in others they terIminate in two hooked claws. Other insects again, of aquatic habits, have the hind limbs modified into paddles; many have the limbs adapted for climbing and clinging; many for running with great rapidity; some for a slow and heavy mode of progress, as the door-beetle; and some again for burrowing like the mole, as the mole-cricket, which well merits its appellation. Thus, then, differently as insects are organized from vertebrate animals, with respect to the general framework of their bodies, and the number position, and conformation

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of the limbs, still we find in the latter, analogous modifications to those presented by the limbs of mammalia, and for the same obvious reasons, to qualify the beings for certain modes of life, and peculiar habits. Differing in anatomical structure as the limbs of insects do, from those of the vertebrata, still a burrowing insect must have scrapers, and a swimming insect paddles; so we may say of the rest. the same time, as we have observed, we cannot trace a series of structural modifications from the limbs of quadrupeds through those of insects, because insects are modelled upon a different type or pattern of organization entirely. As in the crustacea, their external integument serves the purpose of a skeleton, for there is no internal osseous framework.

Concluding with these remarks, we shall proceed to consider, as we proposed, the extent of the sense of tact or touch in the vertebrata, a sense which, residing par excellence in the hand of man, is transferred elsewhere in the vertebrata below him.

CHAPTER IV.

ON THE EQUIVALENTS OF THE HAND AS AN ORGAN

OF TOUCH.

WHAT we have already said respecting the human hand as an organ of touch, distinguished from what we term feeling, or a sensibility to agreeable or painful sensations, we shall not here repeat. We may, however, observe, that as this sense is not needed in great perfection by the lower orders, seeing that man only reasons, compares, and appreciates, so we must not expect to find it of extraordinary delicacy in whatever organ it may be seated among them, and in some it may be almost said to be absent.

In the monkey and ape tribes, which approach the nearest to man in their general conformation—the interval, however, being very greatthe sense of touch undoubtedly resides in the hands. We see these animals try the hardness