Pagina-afbeeldingen
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changed its line of direction, is inferted into the inner part of the chin: by which device, viz. the turn at the loop, the action of the muscle (which in all muscles is contraction) that before would have pulled the jaw up, now as neceffarily draws it down. "The mouth," faith Heifter, "is opened by means of this trochlea in a moft wonderful and elegant manner."

II. What contrivance can be more mechanical than the following, viz. a flit in one tendon to let another tendon pafs through it? This ftructure is found in the tendons which move the toes and fingers. The long tendon, as it is called, in the foot, which bends the first joint of the toe, paffes through the short tendon which bends the second joint; which course allows to the finew more liberty, and a more commodious action than it would otherwife have been capable of exerting*. There is nothing, I believe, in a filk or cotton mill; in the belts, or ftraps, or ropes, by which motion is communicated from one part of the machine to another, that is more artificial, or more evidently fo, than this perforation.

*Chef. Anat. p. 93. 119.

III. The

III. The next circumftance which I fhall mention, under this head of mufcular arrangement, is fo decifive a mark of intention, that it always appeared to me, to fuperfede, in some measure, the neceffity of seeking for any other observation upon the fubject: and that circumftance is, the tendons, which pass from the leg to the foot, being bound down by a ligament at the ancle. The foot is placed at a confiderable angle with the leg. It is manifeft, therefore, that flexible ftrings, paffing along the interior of the angle, if left to themselves, would, when stretched, start from it. The obvious preventative is to tie them down. And this is done in fact. Across the inftep, or rather just above it, the anatomift finds a strong ligament, under which the tendons pafs to the foot. The effect of the ligament as a bandage, can be made evident to the fenses; for if it be cut, the tendons ftart up. The fimplicity, yet the clearness of this contrivance, its exact refemblance to established resources of art, place it amongst the most indubitable manifestations of defign with which we are acquainted.

There is alfo a further ufe to be made of the present example, and that is, as it pre

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cisely contradicts the opinion, that the parts of animals may have been all formed by what is called appetency, i. e. endeavour, perpetuated, and imperceptibly working its effect, through an incalculable ferics of generations. We have here no endeavour, but the reverfe of it; a conftant renitency and reluctance. The endeavour is all the other way. preffure of the ligament confirains the tendons; the tendons react upon the preffure of the ligament. It is impoffible that the ligament fhould ever have been generated by the ex rcife of the tendon, or in the course of that exercife, forasmuch as the force of the tendon perpendicularly refifts the fibre which confines -it, and is conftantly endeavouring, not to form, but to rupture and difplace, the threads of which the ligament is compofed.

Keill has reckoned up, in the human body, four hundred and-forty fix mufcles, diffectible and defcribable; and hath affigned an ufe to every one of the number. This cannot be all imagination.

Bishop Wilkins hath obferved from Galen, that there are, at least, ten feveral qualifica

tions to be attended to in each particular mufcle, viz. its proper figure, its juft magnitude, its fulcrum, its point of action fuppofing the figure to be fixed, its collocation with respect to its two ends the upper and the lower, the place, the position of the whole muscle, the introduction into it of nerves, arteries, veins. How are things, including fo many adjustments, to be made; or, when made, how are they to be put together, without intelligence?

I have fometimes wondered, why we are not ftruck with mechanism in animal bodies, as readily and as ftrongly as we are struck with it, at first fight, in a watch or a mill. One reafon of the difference may be, that animal bodies are, in a great measure, made up of foft, flabby, fubftances, fuch as muscles and membranes; whereas we have been accustomed to trace mechanism in sharp lines, in the configuration of hard materials, in the moulding, chiseling, and filing into fhapes, fuch articles as metals or wood. There is fomething therefore of habit in the cafe: but it is fufficiently evident, that there can be no reason for proper diftinction of the fort. any Mechanism

Mechanism may be displayed in the one kind of substance, as well as in the other.

Although the few inftances we have felected, even as they stand in our description, are nothing short perhaps of logical proofs of defign, yet it must not be forgotten, that, in every part of anatomy, description is a poor fubftitute for inspection. It was well faid by an able anatomist*, and said in reference to the very part of the fubject which we have been treating of, "Imperfecta hæc musculorum defcriptio, non minùs arida eft legentibus, quàm infpectantibus fuerit jucunda corundem præparatio. Elegantiffima enim mechanicês artificia, creberrimè in illis obvia, verbis nonnifi obfcurè exprimuntur; carnium autem ductu, tendinum colore, infertionum proportione, et trochlearium distributione, oculis expofita, omnem fuperant admirationem."

Steno in Blaf. Anat. Animal. p. 2. c. 4.

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