When we see the instrument moving about and feeling on all sides, we must acknowledge that it is the sense of the action of the muscles communicating that motion, which conveys the knowledge of the place or direction of the obstructing body. It appears, therefore, that even in the very lowest creatures, the sense of touch implies the comparison of two distinct senses.

That insects possess the most exquisite organs of sense, must be allowed: but we do not reflect on the extraordinary accuracy with which they measure distances in their movements. This they can only accomplish by an adaptation of the muscular exertion to the sense of vision. The spider, to which I have already alluded-the aranea scenica-when about to leap, elevates itself on its fore-legs, and lifting its head, seems to survey the spot before it jumps; if it spy a small gnat or fly on the wall, it creeps very gently towards it, with short steps, till it comes within a proper distance, and then springs suddenly upon it like a tiger. It will jump two feet to seize upon a bee.*

We have a more curious instance of the precision of the eye and of the adaptation of muscular action, in some of the chætodons, as the chelmon rostratus.t This fish inhabits the Indian rivers, and lives on

the water, when it falls an easy prey. These fishes are kept in large vases for amusement; and if a fly be presented on the end of a twig, they will shoot at it with surprising accuracy. In its natural state it will hit a fly at the distance of from three to six inches.

* Kirby.

The zeus insidiator* has also the same power of forming its mouth into a tube, and squirting at flies, so as to encumber their wings and bring them to the surface of the water. Now, whether we regard these habits in the lower creatures, as bestowed by instinct, or look upon similar powers belonging to ourselves, as acquired properties, we must acknowledge that in both the operation is compound.†

Some would have us believe that the effect of the impression of odours on the nerve of smelling, is exactly similar to that of light on the nerve of vision; and yet they suppose that the impression on the retina alone suffices to inform us of the direction and distance of objects. But of the direction and distance from which odours come, we are quite ignorant until, by turning the head, and directing the nostrils this way and that, we make a comparison, and at length discover on which side the smell is strongest on the sense.

In insects, the motion of the body is rendered subservient to smell, as well as to vision. There is nothing in the mere exercise of the organ of smell that can direct an insect in its flight yet, if a piece of carrion be thrown out, flies will approach it, not by flying in a direct line to it, but by coming towards it in circles. So it is with the bees, in a garden, when attracted to a flower: they may be seen, at first, flying wide, describing circles in their flight, each circle diminishing as they come nearer, until at last they alight upon the object. Having no organ like lungs and thorax to enable them to inhale the effluvia, they make currents in the air, by their mode of flight, so as to impress the nerve of smelling and it is from the sense of the odour being more acute in one part of the circle, that the next wheel is made; and thus they are directed in a line drawn through these circles, to the flower.

We can judge of the direction from which sounds proceed, without turning the ear towards them. That is because the strength of the vibration is unequal on the two sides of the head; and we can readily compare the two impressions, so as to decide upon the direction. But when a person is deaf in

* Belonging to another genus of the same section.

A difficulty will occur to the reader since the rays of light are

refracted at the surface of the water, how does the fish judge of position? Does instinct enable it to do so, or is it experience?

one ear, the comparison is difficult, and he is often mistaken as to the point from which the sound comes; he has more frequent occasion to turn the head, and test the position of the tube of the ear with the strength of the impressions. Accordingly, in mixed company, where there are many speakers, a man in this condition appears positively deaf, from the impossibility of distinguishing minutely the direction of sounds.

The last proof of the necessity of the combination of the muscular sense with the sense of contact will be conclusive. It is not a solitary instance :-A mother while nursing her infant was seized with a paralysis, attended with the loss of muscular power on one side of her body, and the loss of sensibility on the other. The surprising, and indeed the alarming circumstance here was, that she could hold her child to her bosom with the arm which retained muscular power, only so long as she looked to the infant. If surrounding objects withdrew her attention from the state of her arm, the flexor muscles gradually relaxed, and the child was in danger of falling. The details of the case do not belong to our present inquiry; but we see, first, that two distinct properties are possessed by the nerves of the arm, as evinced by the loss of the one, and continuance of the other; secondly, that these two properties exist through different endowments of the nervous system; and, thirdly, that muscular power is insufficient for the exercise of the limbs, without a sensibility to accompany and direct it.

Let me offer another example:-Nothing serves better to make us appreciate the blessings which we enjoy, than examining the organisation of a part which, from its familiarity, and the absolute perfection of its action, we neglect or think meanly of. The lips receive the food, and aid in mastication; they are a principal part of the organ of speech; they are expressive of emotion; they are the most acutely sensible to touch. The vermilion surfaces of the lips possess their exquisite sensibility through minute and delicate villi, into which the extremities of the sensitive nerve are distributed: and these, being covered only with a cuticle the most thin and transparent, afford the ready instrument of touch. Again, a concourse of fine muscles converges to the lips, and surrounds them; and these muscles receive their motor influence from a distinct nerve, coming from

a different quarter of the brain from the sensitive. Now, if this nerve of motion be cut and lose its function, the animal puts its lips to the grains it feeds upon, but cannot gather them. So also, if the nerve of sensation be injured, the animal presses its lips to the food, but wanting the sensibility by which the motion of the lips should be directed, it does not gather them. These facts show that whilst sensibility and motion depend upon different nerves, they are necessarily combined for so simple an act as taking the food into the mouth. As connected with the subject, it is a strange thing to see a person who has every capacity for motion in the lips and tongue, letting the morsel remain in his mouth for hours, without knowing it. The first instance I found of a defect in the lips exactly similar to that produced by the experiment of cutting the nerve of sensation on one side of the face, was in a gentleman who, being under the hands of his dentist, had the nerve of sensation hurt by the pulling of a tooth: having a glass of water given to him, he remarked that the glass was a broken one! The fact being, that the portion of the tumbler in contact with one half of his lips was not felt at all, which gave him the same sensation as if a bit of the glass had been broken away.

The capacity, therefore, of the hand to ascertain the distance, size, weight, form, hardness or softness, roughness or smoothness of objects, results from its having a compound function—from the sensibility of the proper organ of touch, being combined with the consciousness of the motion of the arm, hand, and fingers.

But it is the motion of the fingers that is especially necessary to the sense of touch. These bend, or extend, or expand, or move in every direction, like palpi, with the advantage of embracing the object, feeling it on all its sides, estimating its solidity or its resistance when grasped, moving round it, and gliding over its surfaces, so as to feel every asperity, and be sensible of every slight vibration.

THE PLEASURES ARISING FROM THE MUSCULAR SENSE.

As much of the knowledge usually supposed to be obtained through the organs of the senses, has its source in the exercise of the muscular frame, so we may trace to it some of our chief enjoyments. It may, indeed, be affirmed that nature benevo

lently intends that the vigorous circulation of the blood, and healthful condition both of mind and body, should result from alternations of muscular exertion and repose. The pleasure which proceeds from activity, may be partly due to a gratification naturally arising from the exercise of any kind of power— as that implied by mere dexterity, or the successful pursuit of some field sport, or the accomplishment of a work of art. But independently of such sources of satisfaction, active exercise is followed by weariness, and a desire for rest; and although this condition may not be attended with any describable local pleasure, yet after fatigue, and whilst the active powers are sinking into repose, there is diffused through every part of the frame a feeling almost voluptuous. To this feeling an impatience of rest succeeds. Thus are we urged to follow the alternations of activity and of repose necessary to health; and are invited on from stage to stage of our existence.

We owe other enjoyments to the muscular sense. In modern times comparatively little may be thought of the gratifications arising from motion. Yet we read that the gravest of the Greeks, even of the Romans, studied elegance in their attitudes and movements. Their apparel favoured that display of grace, while their exercises and games contributed to encourage elegance of movement. The dances they performed were not exhibitions of mere exuberance of spirits and activity. It was their pride to combine harmony in the motion of the body and limbs, with majesty of gait; their movements consisted more of the unfolding of the arms, than of the play of the feet,— "their arms sublime, that floated on the air." The Pyrrhic dances were attitudes of combat, or martial movements, performed in correct coincidence with the expression of the music. The spectators, in their theatres, must have had very different associations from ours, to account for the national enthusiasm displayed by the influence of their music, and the rage excited by a mere error in time.

This may remind us that in music the divisions of time depend in some degree on the muscular sense. A man will put down his staff in regulated time; and in his common walk, the sound of his steps will fall into a measure. A boy striking the railing in mere wantonness, will do it with a regular succession of blows. This tendency of the muscular frame to