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viction to his mind; for we draw from nature in a field which has been left strangely neglected, though the nearest to us of all, and of all the most fruitful.
Men proceed in a slow course of advancement in architectural, mechanical, or optical sciences; yet it is found that when an improvement is made, there are all along examples of it in the animal body; which ought to have been marked before, and which might have suggested to us the improvement. It is surprising that this view of the subject has seldom, if ever, been taken seriously, and never pursued. Is the human body formed by an all-perfect Architect, or is it not? And, if the question be answered in the affirmative, does it not approach to something like infatuation, that, possessing such perfect models as we do in the anatomy of the body, we are so prone to neglect them? We undertake to prove that the foundation of the Eddystone lighthouse, the perfection of engineering skill, is not formed on principles so correct as those which have directed the arrangement of the bones of the foot; that the most perfect pillar or kingpost is not adjusted with the accuracy of the hollow bones which support our weight; that the insertion of a ship's mast into the hull is a clumsy contrivance compared with the connexions of the human spine and pelvis; and that the tendons are composed in a manner superior to the last patent cables of Huddart, or the yet more recently improved chaincables of Bloxam.
In two introductory chapters of his "Natural Theology," Archdeacon Paley has given us the advantage of simple, out forcible language, with extreme ingenuity, in illustrating the mechanism of the frame. But for his example, we should have felt some hesitation in making so close a comparison between design, as exhibited by the Creator in the animal structure, and the mere mechanism, the operose and imperfect contrivances, of human
Certainly there may be a comparison; for a superficial and rapid survey of the animal body may convey the notion of an apparatus of levers, pulleys, and ropes, which may be compared with the spring, barrel, and fusee, the wheels and pinions of a watch. But if we study the texture of animal bodies more curiously, and especially if we compare animals with each other
-for instance, the simple structure of the lower creatures with the complicated structure of those higher in the scale of existence-we shall see that, in the lowest links of the chain, animals are so simple, that we should almost call them homogeneous; and yet there, we find life, sensibility, and motion. It is in the animals higher in the scale that we discover parts having distinct endowments, and exhibiting complex mechanical relations. The mechanical contrivances which are so obvious in man, are the provisions for the agency and dominion of an intellectual power over the materials around him.
We mark this early, because there are authors who, looking upon this complexity of mechanism, confound it with the presence of life itself, and think that it is a necessary adjunct-nay, even that life proceeds from it; whereas the mechanism which we have to examine in the animal body, is formed with reference to the necessity of acting upon, or receiving impressions from, things external to the body; an inevitable condition of our state of existence in a material world.
Many have expressed their opinion very boldly on the necessary relation between organisation and life, who have never extended their views to the system of nature. To place man, an intelligent and active being, in this world of matter, he must have properties bearing relation to that matter. The existence of matter implies an agency of certain forces; the particles of bodies must suffer attraction and repulsion, and the bodies formed by the balance of these influences upon their atoms or particles, must have weight or gravity, and possess mechanical properties. So must the living body, independently of its peculiar endowments, have similar composition and qualities, and have certain relations to the solids, fluids, gases, heat, light, electricity, or galvanism, which are around it. Without these, the intellectual principle could receive no impulse-could have no agency and no relation to the material world. The whole body must gravitate or have weight; without which it could neither stand securely nor exert its powers on the bodies around it. But for this, muscular power itself, and all the appliances which are related to that power, would be useless. When, therefore, it is affirmed that organisation or construction is necessary to life, we niay at least pause in giving assent, under the certainty that we see another and a different reason for the con
struction of the body. Thus we perceive, that as the body must have weight to have power, so must it have mechanical contrivance, or arrangement of its parts. As it must have weight, so must it be sustained by a skeleton; and when we examine the bones, which give the body height and shape, we find each column (for in that sense a bone may be first taken) adjusted. with the finest adaptation to the perpendicular weight it has to bear, as well as to the lateral thrusts to which it is subject in the motions of the body.
The bones also act as levers, on the most accurate mechanical principles. And whilst these bones are necessary to give firmness and strength to the frame, it is admirable to observe that one bone never touches another; but a fine elastic material, the cartilage, intervenes betwixt their ends, the effect of which is to give a very considerable degree of elasticity to the whole frame. Without such elasticity a jar would reach the more delicate organs, even in the very recesses of the body, at every violent motion; and, but for this provision, every joint would creak by the attrition of the surfaces of the bones. The bones are surrounded by the flesh or muscles. The muscle is a particular fibrous texture, which alone, of all the materials constituting the frame, possesses the peculiar inherent power or endowment of contracting; it is this power which we are to understand when professional men speak of irritability. The contraction of the muscle bears no proportion to the cause which brings it into operation; more than the touch of the spur upon the horse's side does, as a mechanical impetus, to the force with which the animal propels both himself and rider. Each muscle of the body—and by common estimate there are hundreds—is isolated; and no property of motion is propagated from one to another; they are distinct instruments of motion. The muscles surround the bones, and are so beautifully classed, that in every familiar motion of the limbs some hundreds of them are adjusted in their exact degree, to effect the simplest change in the position of the body. Each fibre of a muscle, and a muscle may contain millions of fibres, is so attached to the tendon, that the whole power is concentrated there; and it is the tendons of the muscles which, like ropes, convey the force of the muscles to the bones. The bones are passive levers; the muscles are the active parts of the frame. With all the seeming intricacy
in the running and crossing of these tendons, they are adjusted accurately on mechanical principles. Where it is necessary, they run in sheaths, or they receive new directions by lateral ligamentous attachments, or there are placed under them smooth and lubricated pulleys, over which they run; and where there is much friction, there is a provision equal in effect to the friction-wheel of machinery. Thus the bones are levers, with their heads most curiously carved and articulated; and joined to the intricate relations of the muscles and tendons, they present on the whole a piece of perfect mechanism.
It is with this texture-the coarsest, roughest portion of the animal frame that a parallel is drawn, when we compare it with the common mechanical contrivances of machinery. But whilst these grosser parts of the living body exhibit a perfection in mechanical adaptation far greater than the utmost ingenuity of man can exhibit in his machinery, let the reader remember that they are surpassed as objects of admiration by the finer organs; such, for example, as the structure of those nerves which carry the mandate of the will to the moving parts; or of the vessels which convey the blood in the circulation, and · where the laws of hydraulics may be finely illustrated; or of those secreting glands, where some will affirm the galvanic influence is in operation, with something subtler than the apparatus of plates and troughs. And could we compare the contrivances of man, with such fine mechanisms in the animal frame, there are structures to be adduced, much more admirable still. The organs of the senses, which are so many inlets for the qualities of surrounding matter to excite corresponding sensations and perceptions, afford us delightful subjects of contemplation; and give proofs of design in the human organism the most conclusive, not only in regard to the system of the body itself, but as it forms a part of the great scheme of the universe.]
OF THE SOLID STRUCTURES OF ANIMAL BODIES.
SUBSTITUTES FOR THE TRUE SKELETON.
It has been shown, in the first chapters, that solidity and gravity are qualities necessary to every inhabitant of the earth; the first, to protect it; the second, that the animal may stand, and possess that resistance which shall make the muscles available for action. In all animal bodies, besides those structures on which their economy and much of their vital functions depend, there must be a texture to give firmness. Without this, the vegetable would have no characteristic form; and animals would want the protection necessary for their delicate organs, and could not move upon their extremities. We have to show with what admirable contrivance, in the different classes of organised beings, this firm fabric is reared; sometimes to protect the parts, as a shell; and sometimes to give them form and motion, as in the skeleton.
In vegetables, as in animals, a certain firm material is essential to support the parts which are the living active organs of their system, and which are so beautiful and interesting. The ligneous or woody fibre is a minute, elastic, semi-opaque filament, which, closing in and adhering to other filaments of the same kind, forms the grain or solid part of the wood. The best demonstration of the office of the woody fibre is in the leaf. When the leaf of a plant is prepared by maceration and putrefaction, and the soft part washed away, there remains an elegant skeleton of wood, which retains the form of the leaf, and is perfectly well suited to support its delicate organisation. It is the same substance which, when accumulated and condensed, gives form and strength to the roots and branches of the oak. And these, though fantastic and irregular in their growth, preserve a mechanical principle of strength; as obvious, to the ship-builder, in the knees of timber, as in the delicate skeleton of the leaf Lord Bacon speaks of "knee-timber that is good for ships that are to be tossed." The woody fibre, though not