Pagina-afbeeldingen
PDF
ePub
[ocr errors]

VII. The Memoirs for the Natural Hif tory of Animals, published by the French Academy, A. D. 1687, furnish us with fome curious particulars in the eye of a camelion. Instead of two eyelids, it is covered by an eyelid with a hole in it. This fingular structure appears to be compenfatory, and to answer to fome other fingularities in the shape of the animal. The neck of the camelion is inflexible. To make up for this, the eye is fo prominent, as that more than half of the ball stands out of the head. By means of which extraordinary projection, the pupil of the eye can be carried by the muscles in every direction, and is capable of being pointed towards every object. But then so unusual an expofure of the globe of the eye, requires for its lubricity and defence, a more than ordinary protection of eyelid, as well as more than ordinary fupply of moisture; yet the motion of an eyelid, formed according to the common conftruction, would be impeded, as it should feem, by the convexity of the organ. The aperture in the lid meets this difficulty. It enables the animal to keep the principal part of the furface of the eye under cover, and to

preferve

preserve it in a due ftate of humidity, without shutting out the light; or without performing every moment a nictitation, which, it is probable, would be more laborious to this animal than to others.

[ocr errors]

VIII. In another animal, and in another part of the animal economy, the fame Memoirs defcribe a most remarkable fubftitution. The reader will remember what we have already obferved concerning the intestinal canal ; that its length, so many times exceeding that of the body, promotes the extraction of the chyle from the aliment, by giving room for the lacteal vessels to act upon it through a greater space. This long inteftine, whereever it occurs, is, in other animals, difpofed in the abdomen from fide to fide in returning folds. But, in the animal now under our notice, the matter is managed otherwife. The fame intention is mechanically effectuated s but by a mechanism of a different kind. The animal of which I fpeak, is an amphibious quadruped, which our authors call the alopecias, or fea fox. The intestine is straight from one end to the other: but in this ftraight, and confequently short inteftine, is a winding, corkscrew, fpiral paffage, through which, the

[ocr errors][merged small]

food, not without feveral circumvolutions, and in fact by a long route, is conducted to its exit. Here the shortnefs of the gut is compenfated by the obliquity of the perforation.

the

IX. But the works of the Deity are known by expedients. Where we fhould look for abfolute deftitution; where we can reckon up nothing but wants; fome contrivance always comes in to supply the privation. A fnail, without wings, feet, or thread, climbs up ftalks of plants, by the fole aid of a vifcid humour discharged from her skin. She adheres to the stems, leaves, and fruits of plants, by means of a sticking plaifter. A muscle, which might feem, by its helpleffness, to lie at the mercy of every wave that went over it, has the fingular power of spinning strong, tendinous threads, by which the moors her fhell to rocks and timbers. A cockle, on the contrary, by means of its ftiff tongue, works for itself a fhelter in the fand. The provisions of nature extend to cafes the moft defperate. A lobfter has a difficulty in its constitution fo great, that one could hardly conjecture before hand how nature would difpofe of it. In most animals, the fkin grows with their growth. If, instead of a foft fkin, there be a fhell,

still it admits of a gradual enlargement. If the fhell, as in the tortoife, confist of several pieces, the acceffion of fubftance is made at the futures. Bivalve fhells grow bigger by receiving an accretion at their edge: it is the fame with spiral fhells at their mouth. The fimplicity of their form admits of this. But the lobster's fhell being applied to the limbs of the body, as well as to the body itself, allows not of either of the modes of growth which are obferved to take place in other shells. Its hardness refifts expanfion; and its complexity renders it incapable of increasing its fize by addition of substance to its edge. How then was the growth of the lobster to be provided for? Was room to be made for it in the old fhell, or was it to be fucceffively fitted with new ones? If a change of fhell became neceffary, how was the lobfter to extricate himfelf from his prefent confinement? How was he to uncafe his buckler, or draw his legs out of his boots? The procefs, which fishermen have observed to take place, is as follows. At certain feasons, the fhell of the lobster grows foft; the animal fwells its body; the feams open, and the claws burft at the joints. When the fhell is thus become loofe upon the body,

X 2

body, the animal makes a fecond effort, and by a tremulous, fpafmodic motion, cafts it off. In this ftate the liberated, but defenceless, fish, retires into holes in the rock.

The released body now fuddenly pushes its growth.

In

about eight-and-forty hours, a fresh concretion of humour upon the surface, i. e. a new shell, is formed, adapted in every part to the increafed dimenfions of the animal. This wonderful mutation is repeated every year.

If there be imputed defects without compenfation, I should suspect that they were defects only in appearance.

the floth has often been

Thus, the body of

reproached for the

flowness of its motions, which has been attributed to an imperfection in the formation of its limbs. But it ought to be obferved, that it is this flowness, which alone fufpends the voracity of the animal. He fafts during his migration from one tree to another; and this faft

may be neceffary for the relief of his overcharged veffels, as well as to allow time for the concoction of the mass of coarse and hard food which he has taken into his ftomach. The tardiness of his pace feems to have reference to the capacity of his organs, and to his propenfities with refpect to food; h. e. is calculated

6

« VorigeDoorgaan »