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CHAPTER XI.

OF THE ANIMAL STRUCTURE REGARDED

AS A MASS.

CONTEMPLATING an animal body in its collective capacity, we cannot forget to notice, what a number of inftruments are brought together, and often within how small a compass. In a canary bird, for inftance, and in the ounce of matter which compofes its body (but which feems to be all employed), we have instruments, for eating, for digesting, for nourishment, for breathing, for generation, for running, for flying, for feeing, for hearing, for smelling; each appropriate; each entirely different from all the reft.

The human, or indeed the animal frame, confidered as a mass or assemblage, exhibits in its compofition three properties, which have long ftruck my mind, as indubitable evidences, not only of defign, but of a great deal of attention and accuracy in profecuting the defign.

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I. The first is, the exact correspondency of the two fides of the fame animal; the right hand answering to the left, leg to leg, eye to eye, one fide of the countenance to the other; and with a precifion, to imitate which in any tolerable degree forms one of the difficulties of ftatuary, and requires, on the part of the artist, a conftant attention to this property of his work, diftinct from every other.

It is the most difficult thing that can be to get a wig made even; yet how feldom is the face awry? And what care is taken that it should not be fo, the anatomy of its bones demonftrates. The upper part of the face is compofed of thirteen bones, fix on each fide, answering each to each, and the thirteenth, without a fellow, in the middle the lower part of the face is in like manner compofed of fix bones, three on each fide, refpectively correfponding, and the lower jaw in the centre. In building an arch could more be done in order to make the curve true, i. e. the parts equi-diftant from the middle, alike in figure and pofition?

The exact refemblance of the eyes, confidering how compounded this organ is in its ftructure, how various and how delicate are the fhades of colour with which its iris is

tinged,

tinged, how differently, as to effect upon appearance, the eye may be mounted in its focket, and how differently in different heads eyes actually are fet, is a property of animal bodies much to be admired. Of ten thousand eyes, I don't know that it would be possible to match one, except with its own fellow; or to diftribute them into fuitable pairs by any other felection than that which obtains.

This regularity of the animal ftructure is rendered more remarkable by the three following confiderations. First, the limbs, feparately taken, have not this correlation of parts; but the contrary of it. A knife drawn down the chine cuts the human body into two parts, externally equal and alike; you cannot draw a ftraight line which will divide a hand, a foot, the leg, the thigh, the cheek, the eye, the ear, into two parts equal and alike. Thofe parts which are placed upon the middle or partition line of the body, or which traverfe that line, as the nofe, the tongue, the lips, may be fo divided, or, more properly fpeaking, are double organs; but other parts cannot. This fhews that the correfpondency which we have been describing does not arife by any neceffity in the nature

of

of the fubject; for, if neceffary, it would be univerfal, whereas it is obferved only in the fyftem or affemblage: it is not true of the separate parts: that is to fay, it is found where it conduces to beauty or utility; it is not found, where it would fubfift at the expence of both. The two wings of a bird always correfpond; the two fides of a feather frequently do not. In centipedes, millepedes, and that whole tribe of infects, no two legs on the fame fide are alike; yet there is the moft exact parity between the legs oppofite to one another.

2. The next circumftance to be remarked, is, that, whilft the cavities of the body are fo configurated, as, externally, to exhibit the most exact correspondency of the oppofite fides, the contents of these cavities have no fuch correfpondency. A fine drawn down the middle of the breaft divides the thorax into two fides exacly fimilar; yet thefe two fides inclofe very different contents. The heart lies on the left fide; a lobe of the lungs on the right; balancing each other, neither in size nor shape. The fame thing holds of the abdomen. liver lies on the right fide, without any fimilar vifcus oppofed to it on the left. The

6

The

fpleen

fpleen indeed is fituated over against the liver; but agreeing with the liver, neither in bulk nor form. There is no equipollency between thefe. The ftomach is a veffel, both irregular in its shape, and oblique in its pofition. The foldings and doublings of the inteftines do not present a parity of fides. Yet that symmetry which depends upon the correlation of the fides, is externally preferved throughout the whole trunk: and is the more remarkable in the lower parts of it, as the integuments are foft; and the shape, confequently, is not, as the thorax is by its ribs, reduced by natural ftays. It is evident, therefore, that the external proportion does not arise from any equality in the shape or preffure of the internal contents. What is it indeed but a correction of inequalities? an adjustment, by mutual compenfation of anomalous forms into a regular congeries? the effect, in a word, of artful, and, if we might be permitted fo, to speak, of ftudied collocation?

3. Similar alfo to this, is the third obfervation? that an internal inequality in the feeding veffels is fo managed, as to produce no inequality in parts which were intended to correfpond. The right arm answers accu

rately

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