COMPENSATION. 
161 
ordinary protection of eyelid, as well as a more than or¬ 
dinary supply of moisture; yet the motion of an eyelid, 
formed according to the common construction, would be 
impeded, as it should seem, 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 surface of the 
eye under cover, and to preserve it in a due state of hu¬ 
midity without shutting out the light; or without perform¬ 
ing every moment a nictitation, which, it is probable, would 
be more laborious to this animal than to others. 
VIII. In another animal, and in another part of the 
animal economy, the same Memoirs describe a most re¬ 
markable substitution. The reader will remember what 
we have already observed 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 intestine, wherever it occurs, 
is in other animals disposed in the abdomen from side to 
side in returning folds. But, in the animal now under 
our notice, the matter is managed otherwise. The same 
intention is mechanically effectuated; but by a mechanism 
of a different kind. The animal of which I speak is an 
amphibious quadruped, which our authors call the alope¬ 
cias, or sea-fox. [PI. XXXI. fig. 2, 3.] The intestine 
is straight from one end to the other: but in this straight, 
and consequently short intestine, is a winding, corkscrew, 
spiral passage, through which the food, not without several 
circumvolutions, and in fact by a long route, is conducted 
to its exit. Here the shortness of the gut is compensated 
by the obliquity of the perforation. 
IX. But the works of the Deity are known by expe¬ 
dients. Where we should look for absolute destitution; 
where we can reckon up nothing but wants, some contri¬ 
vance always comes in to supply the privation. A snail, 
without wings, feet, or thread, climbs up the stalks of 
plants, by the sole aid of a viscid humour discharged from 
her skin. She adheres to the stems, leaves, and fruits 
of plants, by means of a sticking plaster. A muscle , 
which might seem, by its helplessness, to lie at the mercy 
of every wave that went over it, has the singular power of 
spinning strong tendinous threads, by which she moors 
her shell to rocks and timbers. A cockle, on the contrary, 
by means of its stiff tongue, works for itself a shelter in the 
sand. The provisions of nature extend to cases the most 
desperate. A lobster has in its constitution a difficulty so 
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