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principle, and are destined to the same use. In | we had to keep our hearts beating, and our stogeneral they consist of a thin membrane, lying machs at work. Did these things depend, we will close to the side of the vessel, and consequently not say upon our effort, but upon our bidding, our allowing an open passage whilst the stream runs care, or our attention, they would leave us leisure one way, but thrust out from the side by the fluid for nothing else. We must have been continually getting behind it, and opposing the passage of the upon the watch, and continually in fear; nor would blood, when it would how the other way. Where this constitution have allowed of sleep. more than one membrane is employed, the differ It might perhaps be expected, that an organ so ent membranes only compose one valve. Their precious, of such central and primary importance joint action fulfils the office of a valve: for in- as the heart is, should be defended by a case. The stance; over the entrance of the right auricle of fact is, that a membranous purse or bag, made of the heart into the right ventricle, three of these strong, tough materials, is provided for it; holding skins or membranes are fixed, of a triangular figure, the heart within its cavity; sitting loosely and the bases of the triangles fastened to the tiesh; easily about it; guarding its substance, without the sides and summits loose ; but, though loose, contíning its motion; and containing likewise a connected by threads of a determinate length, with spoonful or two of water, just sufficient to keep certain small fleshy prominences adjoining. The the surface of the heart in a state of suppleness effect of this construction is, that when the ven- and moisture. How should such a loose covering tricle contracts, the blood endeavouring to escape be generated by the action of the heart? Does in all directions, and amongst other directions, not the enclosing of it in a sack, answering no pressing upwards, gets between these membranes other purpose but that enclosure, show the care and the sides of the passage; and thereby forces that has been taken of its preservation ? them up into such a position, as that, together, they One use of the circulation of the blood probably constitute, when raised, a hollow cone, (the strings, (amongst other uses) is, to distribute nourishment before spoken of, hindering them from proceeding to the different parts of the body. How minute or separating farther;) which cone, entirely occu- and multiplied the ramifications of the blood-vespying the passage, prevents the return of the sels, for that purpose, are; and how thickly spread, blood into the auricle. A shorter account of the over at least the superficies of the body, is proved matter may be this: so long as the blood proceeds by the single observation, that we cannot priek in its proper course, the membranes which com- the point of a pin into the flesh, without drawing pose the valve are pressed close to the side of the blood, i. e. without finding a blood-vessel. Nor, vessel, and occasion no impediment to the circula- internally, is their diffusion less universal. Bloodtion: when the blood would regurgitate, they are vessels run along the surface of membranes, perraised from the side of the vessel, and, meeting in vade the substance of muscles, penetrate the bones. the middle of its cavity, shut up the channel
. Even into every tooth, we trace, through a small Can any one doubt of contrivance here: or is it hole in the root, an artery to feed the bone, as possible to shut our eyes against the proof of it? well as a vein to bring back the spare blood from
This valve, also, is not more curious in its struc. it; both which, with the addition of an accompanyture, than it is important in its office. Upon the ing nerve, form a thread only a little thicker than play of the valve, even upon the proportioned a horse-hair. length of the strings or fibres which check the as Wherefore, when the nourishment taken in at ceni of the membranes, depends, as it should the mouth has once reached, and mixed itself with seem, nothing less than the life itself of the ani- the blood, every part of the body is in the way of mal.' We may here likewise repeat, what we be being supplied with it. And this introduces an. fore observed concerning some of the ligaments of other grand topic, namely, the manner in which the body, that they could not be formed by any the aliment gets into the blood ; which is a subject action of the parts themselves. There are cases distinct from the preceding, and brings us to the in which, although good uses appear to arise from consideration of another entire system of vesse Is. the shape or configuration of a part, yet that shape II. For this necessary part of the animal econo or configuration itself may seem to be produced my, an apparatus is provided, in a great measure by the action of the part, or by the action or pres- capable of being what anatomists call demonstrated, sure of adjoining parts. Thus the bend and the that is, shown in the dead body;--and a line or internal smooth concavity of the ribs, may be at- course of conveyance, which we can pursue by tributed to the equal pressure of the soft bowels; our examinations. the particular shape of some bones and joints, to First, the food descends by a wide passage into the traction of the annexed muscles, or to the po- the intestines, undergoing two great preparations sition of contiguous muscles. But valves could on its way: one, in the mouth by mastication and not be so formed. Action and pressure are all moisture-(can it be doubted with what design against them. The blood, in its proper course, the teeth were placed in the road to the stomach, has no tendency to produce such things; and in its or that there was choice in fixing them in this improper or reflected current, has a tendency to situation ?) the other, by digestion in the stomach prevent their production. Whilst we see, there- itself. Of this last surprising dissolution I say fore, the use and necessity of this machinery, we nothing; because it is chymistry, and I am endeacan look to no other account of its origin or forma vouring to display mechanism. The figure and tion than the intending mind of a Creator. Nor position of the stomach (I speak all along with a can we without admiration reflect, that such thin reference to the human organ) are calculated for membranes, such weak and tender instruments detaining the food long enough for the action of as these valves are, should be able to hold out for its digestive juice. It has the shape of the pouch seventy or eighty years.
of a bagpipe; lies across the body; and the pylorus, Here also we cannot consider but with grati- or passage by which the food leaves it, is sometude, how happy it is that our vital motions are what higher in the body than the cardia, or orifice incoluntary." We should have enough to do, if by which it enters so that it is by the contraction
of the muscular coat of the stomach, that the con, which we call chyle, are, by a series of gentle tents, after having undergone the application of compressions, squeezed into the narrow orifices the gastric menstruum, are gradually pressed out of the lacteal veins. Thirdly, it was necessary In dogs and cats, this action of the coats of the that these tubes, which we denominate lacteals, stomach has been displayed to the eye. It is a or their mouths at least, should be made as narslow and gentle undulation, propagated from one row as possible, in order to deny admission into orifice of the stomach to the other. For the same the blood to any particle which is of size enough reason that I omitted, for the present, offering any to make a lodgment afterward in the small arteries, observation upon the digestive fluid, I shall say and thereby to obstruct the circulation : and it was nothing concerning the bile or the pancreatic juice, also necessary that this extreme tenuity should be farther than to observe upon the mechanism, riz compensated by multitude; for a large quantity of that from the glands in which these secretions are chyle (in ordinary constitutions, not less, it has elaborated, pipes are laid into the first of the intes- been computed, than two or three quarts in a day) tines, through which pipes the product of each is, by some means or other, to be passed through gland flows into that bowel
, and is there mixed them. Accordingly, we find the number of the with the aliment, as soon almost as it passes the lacteals exceeding all powers of computation; and stomach; adding also as a remark, how grievously their pipes so fine and slender, as not to be visible, this same bile offends the stomach itself, yet unless filled, to the naked eye; and their orifices, cherishes the vessel that lies next to it.
which open into the intestines, so small, as not Secondly, We have now the aliment in the in- to be discernible even by the best microscope. testines, converted into pulp; and, though lately Fourthly, the main pipe which carries the chyle consisting of ten different viands, reduced to nearly from the reservoir to the blood, viz. the thoracic a uniform substance, and to a state fitted for yield- duct, being fixed in an almost upright position, ing its essence, which is called chyle, but which and wanting that advantage of propulsion which is milk, or more nearly resembling milk than any the arteries possess, is furnished with a succession other liquor with which it can be compared. For of valves to check the ascending fluid, when once the straining of this fluid from the digested aliment it has passed them, from falling back. These in the course of its long progress through the valves look upward, so as to leave the ascent free, body, myriads of capillary tubes, i. e. pipes as but to prevent the return of the chyle, if, for want small as hairs, open their orifices into the cavity of sufficient force to push it on, its weight should of every part of the intestines. These tubes, at any time cause it to descend. Fifthly, the which are so fine and slender as not to be visible chyle enters the blood in an odd place, but perhaps unless when distended with chyle, soon unite into the most commodious place possible, riz. at a large larger branches. The pipes, formed by this union, vein in the neck, so situated with respect to the terminate in glands, from which other pipes of a circulation, as speedily to bring the mixture to the still larger diameter arising, carry the chyle from heart. And this seems to be a circumstance of all parts, into a common reservoir or receptacle. great moment; for had the chyle entered the blood This receptacle is a bag of size enough to hold at an artery, or at a distant vein, the fluid, comabout two table-spoons full; and from this vessel posed of the old and the new materials, must have a duct or main pipe proceeds, climbing up the performed a considerable part of the circulation, back part of the chest, and afterward creeping before it received that churning in the lungs, along the gullet till it reach the neck. Here it which is, probably, necessary for the intimate and meets the river: here it discharges itself into a perfect union of the old blood with the recent large vein, which soon conveys the chyle, now chyle. Who could have dreamt of a communicaflowing along with the old blood, to the heart. tion between the cavity of the intestines and the This whole route can be exhibited to the eye; no left great vein of the neck? Who could have thing is left to be supplied by imagination or con- suspected that this communication should be the jecture. Now, beside the subserviency of this medium through which all nourishment is derived structure, collectively considered, to a manifest to the body; or this the place, where, by a side-inlet, and necessary purpose, we may remark two or the important junction is formed between the three separate particulars in it, which show, not blood and the material which feeds it ? only the contrivance, but the perfection of it. We We postponed the consideration of digestion, may remark, first, the length of the intestines, lest it should interrupt us in tracing the course of which, in the human subject, is six times that of the food to the blood; but in treating of the alithe body. Simply for a passage, these voluminous mentary system, so principal a part of the process bowels, this prolixity of gut, seems in no wise ne- cannot be omitted. cessary; but in order to allow time and space for Of the gastric juice, the immediate agent by the successive extraction of the chyle from the which that change which food undergoes in our digested aliment, namely, that the chyle which stomachs is effected, we shall take our account escapes the lacteals of one part of the guts may be from the numerous, careful, and varied experitaken up by those of some other part, the length ments of the Abbé Spallanzani. of the canal is of evident use and conduciveness. 1. It is not a simple diluent, but a real solvent, Secondly, we must also remark their peristaltic A quarter of an ounce of beef had scarcely touchmotion; which is made up of contractions, follow-ed the stomach of a crow, when the solution being one another like waves upon the surface of a gun. fluid, and not unlike what we observe in the body 2. It has not the nature of saliva; it has not of an earth-worm crawling along the ground; and the nature of the bile; but is distinct from both. which is effected by the joint action of longitudinal By experiments out of the body it appears, that and of spiral, or rather perhaps of a great number neither of these secretions acts upon alimentary of separate semicircular fibres. This curious ac- substances, in the same manner as the gastríc tion pushes forward the grosser part of the ali- juice acts. ment, at the same time that the more subtile parts, 3. Digestion is not putrefaction: for the digest
mg fluid resists putrefaction most pertinaciously; the gastric juice, not having been weakened by nay, not only checks its farther progress, but re- disease, retains its activity,) it has been known to stores putrid substances.
eat a hole through the bowel which contains it.* 4. li is not a fermentative process: for the so- How nice is this discrimination of action, yet how lution begins at the surface, and proceeds towards necessary! the centre, contrary to the order in which ferment But to return to our hydraulics. ation acts and spreads.
III. The gall-bladder is a very remarkable con5. It is not the digestion of heat : for the cold trivance. It is the reservoir of a canal. It does maw of a cod or sturgeon will dissolve the shells not form the channel itself, i. e. the direct comof crabs or lobsters, harder than the sides of the munication between the liver and the intestine, stomach which contains them.
which is by another passage, viz. the ductus hepaIn a word, animal digestion carries about it the ticus, continued under the name of the ductus commarks of being a power and a process completely munis; but it lies adjacent to this channel, joinsui generis ; distinct from every other; at least ing it by a duct of its own, the ductus cysticus : from every chymical process with which we are j by which structure it is enabled, as occasion may acquainted. And the most wonderful thing about require, to add its contents to, and increase the it is its appropriation; its subserviency to the par- flow of bile into the duodenum. And the positicular economy of each animal. The gastric tion of the gall-bladder is such as to apply this juice of an owl, falcon, or kite, will not touch grain; structure to the best advantage. In its natural no, not even to finish the macerated and half-di- situation, it touches the exterior surface of the gested pulse which is left in the crops of the spar- stomach, and consequently is compressed by the rows that the bird devours. In poultry, the tritu- distention of that vessel : the effect of which comration of the gizzard, and the gastric juice, con- pression is to force out from the bag, and send inspire in the work of digestion. The gastric juice to the duodenum, an extraordinary quantity of will not dissolve the grain whilst it is whole. En- bile, to meet the extraordinary demand which the tire grains of barley, enclosed in tubes or sphe- repletion of the stomach by food is about to occarules, are not affected by it. But if the same sion.t Cheselden describes the gall-bladder as grain be by any means broken or ground, the gas- seated against the duodenum, and thereby liable tric juice immediately lays hold ofoit. Here then to have its fiuid pressed out, by the passage of the is wanted, and here we find, a combination of aliment through that cavity; which likewise will mechanism and chymistry. For the preparatory have the effect of causing it to be received into the grinding, the gizzard lends its mill. And as all intestine, at a right time, and in a due proportion. mill-works should be strong, its structure is so, be There may be other purposes answered by this yond that of any other muscle belonging to the contrivance; and it is probable that there are. animal. The internal coat also, or lining of the The contents of the gall-bladder are not exactly gizzard, is, for the same purpose, hard and carti- of the same kind as what passes from the liver laginous. ' But, forasmuch as this is not the sort through a direct passage. It is possible that the of animal substance, suited for the reception of gall may be changed, and for some purposes meglands or for secretion, the gastric juice, in this liorated, by keeping. family, is not supplied, as in membranous sto. The entrance of the gall-duct into the duodemachs, by the stomach itself, but by the gullet, in num furnishes another observation. Whenever which the feeding glands are placed, and from either smaller tubes are inserted into larger tubes, which it trickles down into the stomach.
or tubes into vessels and cavities, such receiving In sheep, the gastric fluid has no effect in di- tubes, vessels, or cavities, being subject to muscugesting plants, unless they have been previously lar constriction, we always find a contrivance to masticated. It only produces a slight maceration, prevent regurgitation. In some cases, valves are nearly such as common water would produce, in used; in other cases, amongst which is that now a degree of heat somewhat exceeding the medium before us, a different expedient is resorted to, which temperature of the atmosphere. But provided may be thus described: The gall-duct enters the that the plant has been reduced to pieces by chew-duodenum obliquely: after it has pierced the first ing, the gastric juice then proceeds with it, first coat, it runs near two fingers' breadth between the by softening its substance; next by destroying its coats, before it opens into the cavity of the intes: natural consistency; and lastly, by dissolving it tine. The same contrivance is used in another so completely, as not even to spare the toughest part, where there is exactly the same occasion for and most stringy parts, such as the nerves of the it
, viz. in the insertion of the ureters in the blad leaves.
der. These enter the bladder near its neck, runSo far our accurate and indefatigable Abbé.- ning obliquely for the space of an inch between Dr. Stevens, of Edinburgh, in 1777, found, by ex- its coats. It is, in both cases, sufficiently eviperiments tried with perforated balls, that the gas- dent, that this structure has a necessary mechatric juice of the sheep and the ox speedily dissolved nical tendency to resist regurgitation: for whatever vegetables, but made no impression upon beef, force acts in such a direction as to urge the fluid mutton, and other animal bodies. Dr. Hunter back into the orifices of the tubes, must, at the discovered a property of this fluid, of a most cu- same time, stretch the coats of the vessels, and rious kind; viz. that in the stomachs of animals thereby compress that part of the tube which is which feed upon flesh, irresistibly as this fluid acts included between them. upon animal substances, it is only upon the dead IV. Amongst the vessels of the human body substance that it operates at all. The living fibre the pipe which conveys the saliva from the place suffers no injury from lying in contact with it. where it is made, to the place where it is wanted, Worms and insects are found alive in the stomachs of such animals. The coats of the human
. Phil. Trans. vol. Ixij. p. 447. | Keill's Anat. p. 64. stomach, in a healthy state, are insensible to its
1 Anat. p. 164. & Keill. (from Malpighius,) p. 63. presence; yet in cases of sudden death, (wherein! Keill's Anat. p. 62. 1 Cheselden's Anat. p 260
deserves to be reckoned amongst the most intelli- j glottis : I do not mean in the same individual, but gible pieces of mechanism with which we are ac in a succession of generations. Not only the acquainted. The saliva, we all know, is used in tion of the parts has no such tendency, but the the mouth : but much of it is produced on the animal could not live, nor consequently the parts outside of the cheek, by the parotid gland, which act, either without it, or with it in a half-formed lies between the ear and the angle of the lower state. The species was not to wait for the jaw. In order to carry the secreted juice to its gradual formation or expansion of a part which destination, there is laid from the gland, on the was, from the first, necessary to the life of the inoutside, a pipe, about the thickness of a wheat dividual. straw, and about three fingers' breadth in length; Not only is the larynx curious, but the whole which, after riding over the masseter muscle, bores wind-pipe possesses a structure adapted to its pefor itself a hole through the very middle of the culiar office. It is made up (as any one may percheek; enters by that hole, which is a complete ceive by putting his fingers to his throat) of stout perforation of the buccinator muscle, into the cartilaginous ringlets, placed at small and equal mouth; and there discharges its fluid very co distances from one another. Now this is not the piously
case with any other of the numerous conduits of V. Another exquisite structure, differing in the body. The use of these cartilages is to keep deed from the four preceding instances, in that it the passage for the air constantly open ; which does not relate to the conveyance of fluids, but they do mechanically. A pipe with soft memstill belonging, like these, to the class of pipes or branous coats, liable to collapse and close when conduits of the body, is seen in the larnyr. We empty, would not have answered here; although all know that there go down the throat two pipes, this be the general vascular structure, and a strucone leading to the stomach, the other to the lungs; ture which serves very well for those tubes which the one being the passage for the food, the other are kept in a state of perpetual distension by the for the breath and voice: we know also that both fiuid they enclose, or which afford a passage to these passages open into the bottom of the mouth; solid and protruding substances. the gullet, necessarily, for the conveyance of food; Nevertheless (which is another particularity and the wind-pipe, for speech and the modulation well worthy of notice,) these rings are not comof sound, not much less so: therefore the difficulty plete, that is, are not cartilaginous and stiff all was, the passages being so contiguous, to prevent round; but their hinder part, which is contiguous the food, especially the liquids, which we swal- to the gullet, is membranous and soft, easily yieldlow into the stomach, from entering the winding to the distensions of that organ occasioned by pipe, i. e. the road to the lungs; the conse- the descent of solid food. The same rings are also quence of which error, when it does happen, is bevelled off at the upper and lower edges, the better perceived by the convulsive throes that are instant. to close upon one another, when the trachea is ly produced. This business, which is very nice, is compressed or shortened. managed in this manner. The gullet (the pas The constitution of the trachea may suggest sage for food) opens into the mouth like the cone likewise another reflection. The membrane or upper part of a funnel, the capacity of which which lines its inside, is, perhaps, the most sensiforms indeed the bottom of the mouth. Into the ble, irritable membrane of the body. It rejects side of this funnel, at the part which lies the the touch of a crumb of bread, or a drop of water, lowest, enters the wind-pipe, by a chink or slit, with a spasm which convulses the whole frame; with a lid or flap, like a litile tongue, accurately yet, left to itself, and its proper office, the intro fitted to the orifice. The solids or liquids which mission of air alone, nothing can be so quiet. It we swallow, pass over this lid or flap, as they de- does not even make itself felt; a man does not scend by the funnel into the gullet. Both the know that he has a trachea. This capacity of weight of the food, and the action of the muscles perceiving with such acuteness, this impatience of concerned in swallowing, contribute to keep the offence, yet perfect rest and ease when let alone, lid close down upon the aperture, whilst any thing are properties, one would have thought, not likely is passing; whereas, by means of its natural carti- to reside in the same subject. It is to the junclaginous spring, it raises itself a little, as soon as tion, however, of these almost inconsistent qualithe food is passed, thereby allowing a free inletties, in this, as well as in some other delicate parts and outlet for the respiration of air by the lungs of the body, that we owe our safety and our comSuch is its structure: and we may here remark fort ;-our safety to their sensibility, our comfort the almost complete success of the expedient, viz. to their repose. how seldom it fails of its purpose, compared with The larynx, or rather the whole wind-pipe the number of instances in which it fulfils it. taken together, (for the larynx is only the upper Reflect how frequently we swallow, how con- part of the wind-pipe,) besides its other uses, is stantly we breathe. In a city feast, for example, also a musical instrument, that is to sav, it is what deglutition, what anhelation! yet does this mechanism expressly adapted to the modulation little cartilage, the epiglottis, so effectually inter- of sound; for it has been found upon trial, that, pose its office, so securely guard the entrance of by relaxing or tightening the tendinous bands at ihe wind-pipe, that whilst morsel after morsel, the extremity of the wind-pipe, and blowing in at draught after draught, are coursing one another the other end, all the cries and notes might be over it, an accident of a crumb or a drop slipping produced of which the living animal was capable. into this passage (which nevertheless must be It can be sounded, just as a pipe or flute is opened for the breath every second of time,) sounded. excites in the whole company, not only alarm by Birds, says Bonnet, have, at the lower end of its danger, but surprise by its novelty. Not two the wind-pipe, a conformation like the reed of a guests are choked in a century.
hautboy, for the modulation of their notes, A There is no room for pretending that the action tuneful bird is a ventriloquist. The seat of the of the parts may have gradually formed the epi- song is in the breast.
The use of the lungs in the system has been often within how small a compass. It is a cluster said to be obscure; one use however is plain, of contrivances. In a canary-bird, for instance, though in some sense external to the system, and and in the single ounce of matter which composes that is, the formation, in conjunction with the his body, (but which seems to be all employed,) larynx, of voice and speech. They are, to animal i we have instruments for eating, for digesting, for utterance, what the bellows are to the organ. nourishment, for breathing, for generation, for
running, for flying, for seeing, for hearing, for For the sake of method, we have considered smelling; each appropriate,-each entirely differanimal bodies under three divisions; their bones, ent from all the rest. their muscles, and their vessels: and we have The human, or indeed the animal frame, constated our observations upon these parts separately. sidered as a mass or assemblage, exhibits in its But this is to diminish the strength of the argu- composition three properties, which have long ment. The wisdom of the Creator is seen, not in struck my mind as indubitable evidences, not only their separate but their collective action ; in their of design, but of a great deal of attention and acmutual subserviency and dependance; in their con- curacy in prosecuting the design. tributing together to one effect, and one nise. It I. The first is, the exact correspondency of the has been said, that a man cannot lift his hand to two sides of the same animal: the right hand anhis head, without finding enough to convince him swering to the left, leg to leg, eye to eye, one side of the existence of a God. And it is well said; of the countenance to the other; and with a prefor he has only to reflect, familiar as this action is, cision, to imitate which in any tolerable degree and simple as it seems to be, how many things forms one of the difficulties of statuary, and requires are requisite for the performing of it: how many on the part of the artist, a constant attention to things which we understand, to say nothing of this property of his work, distinct from every other. many more, probably, which we do not; viz. first, It is the most difficult thing that can be to get a long, hard, strong cylinder, in order to give to a wig made even; yet how seldom is the face the arm its firmness and tension; but which, awry? And what care is taken that it should not being rigid, and, in its substance, inflexible, can be so, the anatomy of its bones demonstrates. The only turn upon joints: secondly, therefore, joints upper part of the face is composed of thirteen for this purpose; one at the shoulder to raise the bones, six on each side, answering each to each, arm, another at the elbow to bend it; these joints and the thirteenth, without a fellow, in the midcontinually fed with a soft mucilage to make the dle; the lower part of the face is in like manner parts slip easily upon one another, and holden composed of six bones, three on each side respecttogether by strong braces, to keep them in their ively corresponding, and the lower jaw in the position: then, thirdly, strings and wires, i. e. centre. In building an arch, could more be done in muscles and tendons, artificially inserted for the order to make the curve true, i. e. the parts equi-dispurpose of drawing the bones in the directions in tant from the middle, alike in figure and position? which the joints allow them to move. Hitherto we The exact resemblance of the eyes, considering seem to understand the mechanism pretty well; how compounded this organ is in its structure, and, understanding this, we possess enough for how various and how delicate are the shades of our conclusion: nevertheless, we have hitherto colour with which its iris is tinged; how differonly a machine standing still; a dead organization, ently, as to effect upon appearance, the eye may
-an apparatus. To put the system in a state of be mounted in its socket, and how differently in activity; to set it at work; a farther provision is different heads eyes actually are set,—is a propernecessary, viz. a communication with the brain ty of animal bodies much to be admired. Of'ten by means of nerves. We know the existence of thousand eyes, I do not know that it would be this communication, because we can see the com- possible to match one, except with its own fellow; or municating threads, and can trace them to the to distribute them into suitable pairs by any other brain: its necessity we also know, because if the selection than that which obtains. thread be cut, if the communication be intercepted, This regularity of the animal structure is renthe muscle becomes paralytic: but beyond this we dered more remarkable by the three following conknow little; the organization being too minute and siderations. First, the limbs, separately taken, subtile for our inspection.
have not this correlation of parts, but the contrary To what has been enumerated, as officiating in of it. A knife drawn down the chine, cuts the the single act of a man's raising his hand to his human body into two parts, externally equal and head, must be added likewise, all that is necessary, alike; you cannot draw a straight line which and all that contributes to the growth, nourishment, will divide a hand, a foot, the leg, the thigh, the and sustentation, of the limb, the repair of its cheek, the eye, the ear, into two parts equal and waste, the preservation of its health: such as the alike. Those parts which are placed upon the circulation of the blood through every part of it ; middle or partition line of the body, or which its lymphatics, exhalants, absorbents; its excre traverse that line, as the nose, the tongue, the lips, tions and integuments. All these share in the may be so divided, or, more properly speaking, are result; join in the efiect: and how all these, or double organs: but other parts cannot. This any of them, come together without a designing, shows that the correspondency which we have disposing intelligence, it is impossible to conceive. been describing, does not arise by any necessity
in the nature of the subject : for, if necessary, it
would be universal; whereas it is observed only CHAPTER XI.
in the system or assemblage: it is not true of the Of the Animal Structure regarded as a Mass.
separate parts; that is to say, it is found where it
conduces to beauty or utility; it is not found, CONTEMPLATING an animal body in its collect- where it would subsist at the expense of both. ive capacity, we .cannot forget to notice what a The two wings of a bird always correspond : the number of instruments are brought together, and two sides of a feather frequently do not. In centi