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of its underground lise. It is a special purpose, specially consulted throughout. The form of the seet fixes the character of the animal. They are so many shovels: they determine its action to that of rooting in the ground; and every thing about its body agrees with this destination. The cylindrical figure of the mole, as well as the compactness of its form, arising from the terseness of its limbs, proportionally lessens its labour; because, according to its bulk, it thereby requires the least possible quantity of earth to be removed for its progress. It has nearly the fame structure of the face and jaws as a swine, and the fame office for them. The nose is sharp, slender, tendinous, strong; with a pair of nerves going down to the end of it. The plush covering, which, by the smoothness, closeness, and polish of the short piles that compose it, rejects the adhesion of almost every species of earth, defends the animal from cold and wet, and from the impediment, which it would experience by the mold sticking to its body. From foils of all kinds the little pioneer comes forth bright and clean. Inhabiting dirt, it is, of all animals, the neatest.
But what I have always most admired in the mole is its eyes. This animal occasionally visiting the surface, and wanting, for its fasety and direction, to be informed when it does so, or when it approaches it, a perception of, light was necessary. I do not know that the clearness of light depends at all upon the size of the organ. What is gained by the largeness or prominence of the globe of the eye is width in the field of vision. Such a capacity would be of no use to an animal which was to seek its food in the dark. The mole did not want to look about it; nor would a large advanced eye have been easily defended from the annoyance, to which the life of the animal must constantly expose it. How indeed was the mole, working its way under ground, to guard its eyes at all? In order to meet this ( difficulty, the eyes are made scarcely larger than the head of a corking pin; and these minute globules are funk so deep in the skull, and lie so sheltered within the velvet of its covering, as that any contraction of what may be called the eyebrows, not only closes up the apertures which lead to the eyes, but presents a cushion, as it were, to any sharp pr protruding substance, which might push u 4 against
against them. This aperture even in its ordinary state is like a pin hole in a piece of velvet, scarcely pervious to loose particles of earth.
Observe then, in this structure, that which we call relation. There is no natural connection between a small sunk eye and a shovel palmated foot. Palmated feet might have been joined with goggle eyes; or small eyes might have been joined with feet of any other form. What was it therefore which brought them together in the mole? That which brought together the barrel, the chain, and the fusee, in a watch: design; and design, in both cases, inserred, from the relation which the parts bear to one another in the prosecution of a common purpose. As hath already been observed, there are different ways of stating the relation, according as we set out from a different part. In the instance before us, we may either consider the shape of the feet, as qualifying the animal for that mode of lise and inhabitation, to which the structure of its eye confines it; or we may consider the structure of the eye, as the only one which would have spiced with the action to which
th« the feet are adapted. The relation is manifest, whichever of the parts related we place first in the order of our consideration. In a word: the feet of the mole are made for digging; the neck, nose, eyes, ears, and skin, are peculiarly adapted to an underground life: and this is what I call relation,
Compensation is a species of relation. It is relation, when the defeat of one part, or of one organ, are supplied by the structure of another part, or of another organ. Thus,
I. The short, unbending neck of the elephants is compenfated by the length and flexibility of his proboscis. He could not have reached the ground without it: or, if it be supposed that he might have fed upon the fruit, leaves, or branches of trees, how was he to drink? Should it be aiked, Why is the elephant's neck so short? it may be answered that the weight of a head so heavy could not have been supported at the end, of a longer lever. To a form therefore, in some respects necessary, but in some respects also inadequate to the occasions of the animal, a supplement is added, which exactly makes up the deficiency under which he laboured.