(which is the sort of relation that is perhaps most striking,) are such as the following:

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 mould sticking to its body. From soils 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 safety 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 sight 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

I. In the swan; the web-foot, the spoonbill, the long neck, the thick down, the graminivorous stomach, bear all a relation to one another, inasmuch as they all concur in one design, that of supplying the occasions of an aquatic fowl, floating upon the surface of shallow pools of water, and seeking its food at the bottom. Begin with any one of these particularities of structure, and observe how the rest follow it. The web-foot qualifies the bird for swimming the spoon-bill enables it to graze. But how is an animal, floating upon the surface of pools of water, to graze at the bottom, except by the mediation of a long neck? A long neck accordingly is given to it. Again, a warm-blooded animal, which was to pass its life upon water, required a defence against the coldness of that element. Such a defence is furnished to the swan, in the muff in which its body is wrapped. But all this outward apparatus would have been in vain, if the intes-seek its food in the dark. The mole did not inal system had not been suited to the diges- want to look about it; nor would a large adtion of vegetable substances. I say, suited to vanced eye have been easily defended from the the digestion of vegetable substances; for it is annoyance to which the life of the animal must well known, that there are two intestinal sys- constantly expose it. How indeed was the tems found in birds: one with a membranous mole, working its way under ground, to guard stomach and a gastric juice, capable of dissolv-its eyes at all? In order to meet this difficul. ing animal substances alone; the other with a ty, the eyes are made scarcely larger than the crop and gizzard, calculated for the moisten-head of a corking-pin; and these minute gloing, bruising, and afterwards digesting, of vegetable aliment.

bules are sunk so deeply in the skull, and lie so sheltered within the velvet of its covering, Or, set off with any other distinctive part in as that any contraction of what may be called the body of the swan; for instance, with the the eye-brows, not only closes up the apertures long neck. The long neck, without the web- which lead to the eyes, but presents a cushion, foot, would have been an encumbrance to the as it were, to any sharp or protruding substance bird; yet there is no necessary connexion be- which might push against them. This apertween a long neck and a web-foot. In fact, ture, even in its ordinary state, is like a pinthey do not usually go together. How hap-hole in a piece of velvet, scarcely pervious to pens it, therefore, that they meet, only when loose particles of earth. a particular design demands the aid of both ? Observe then, in this structure, that which II. This mutual relation, arising from a we call relation. There is no natural connexsubserviency to a common purpose, is very ob-ion between a small sunk eye and a shovel servable also in the parts of a mole. The palmated foot. Palmated feet might have been strong short legs of that animal, the palmated joined with goggle eyes; or small eyes might feet armed with sharp nails, the pig-like nose, have been joined with feet of any other form. the teeth, the velvet coat, the small external What was it therefore which brought them ear, the sagacious smell, the sunk protected together in the mole? That which brought eye, all conduce to the utilities or to the safety together the barrel, the chain, and the fusee of its underground life. It is a special pur- in a watch,-design; and design, in both cases, pose, specially consulted throughout. The inferred from the relation which the parts form of the feet fixes the character of the ani- bear to one another in the prosecution of a mal. They are so many shovels; they de-common purpose. As hath already been obtermine 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, proportionably 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 same structure of the face and jaws as a swine, and the same affice for them. The nose is sharp, slender,

served, 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 life and inhabitation to which the structure of its eyes confines it; or we may consider the structure of the eye, as the only one which would have suited with the action to which 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 vantage,) but of consummate art, and, as I the mole are made for digging; the neck, nose, may say, of elaborate preparation, in accomeyes, ears, and skin, are peculiarly adapted to plishing that design. an underground life; and this is what I call relation.

CHAPTER XVI.

COMPENSATION.

COMPENSATION is a species of relation. It is relation when the defects of one part, or of one organ, are supplied by the structure of another part or of another organ. Thus,

II. The hook in the wing of a bal is strict. ly a mechanical, and also, a compensating contrivance. At the angle of its wing there is a bent claw, exactly in the form of a hook, by which the bat attaches itself to the sides of rocks, caves, and buildings, laying hold of crevices, joinings, chinks, and roughnesses. It hooks itself by this claw; remains suspended by this hold; takes its flight from this position: which operations compensate for the decrepitude of its legs and feet. Without her hook, the bat would be the most helpless of all animals. She can neither run upon her feet, I. The short unbending neck of the elephant, nor raise herself from the ground. These inis compensated by the length and flexibility of abilities are made up to her by the contrivance his proboscis. He could not have reached the in her wing: aud in placing a claw on that ground without it; or, if it be supposed that part, the Creator has deviated from the anahe might have fed upon the fruit, leaves, or logy observed in winged animals.—A singular branches of trees, how was he to drink? Should defect required a singular substitute. it be asked, Why is the elephant's neck so III. The orane-kind are to live and seek short? it may be answered, that the weight their food amongst the waters; yet, having no of a head so heavy could not have been sup-web-feet, are incapable of swimming. To make ported at the end of a longer lever. To a form, up for this deficiency, they are furnished with therefore, in some respects necessary, but in long legs for wading, or long bills for groping; some respects also inadequate to the occasions or usually with both. This is compensation. of the animal, a supplement is added, which But I think the true reflection upon the preexactly makes up the deficiency under which sent instance is, how every part of nature is he laboured. tenanted by appropriate inhabitants. Not onIf it be suggested that this proboscis may ly is the surface of deep waters peopled by nuhave been produced, in a long course of gene-merous tribes of birds that swim, but marshes rations, by the constant endeavour of the ele- and shallow pools are furnished with hardly phant to thrust out his nose (which is the ge- less numerous tribes of birds that wade. neral hypothesis by which it has lately been IV. The common parrot has, in the strucattempted to account for the forms of animat-ture of its beak, both an inconveniency, and a ed nature,) I would ask, How was the animal compensation for it. When I speak of an into subsist in the mean time, during the pro- conveniency, I have a view to a dilemma which cess, until this prolongation of snout were completed? What was to become of the individual, whilst the species was perfecting?

frequently occurs in the works of nature, viz. that the peculiarity of structure by which an organ is made to answer one purpose, necesOur business at present is, simply to point sarily unfits it for some other purpose. This out the relation which this organ bears to the is the case before us. The upper bill of the peculiar figure of the animal to which it be- parrot is so much hooked, and so much overlongs. And herein all things correspond. The laps the lower, that if, as in other birds, the necessity of the elephant's proboscis arises from lower chap alone had motion, the bird could the shortness of his neck; the shortness of the scarcely gape wide enough to receive its food : neck is rendered necessary by the weight of yet this hook and overlapping of the bill could the head. Were we to enter into an exami- not be spared, for it forms the very instrument nation of the structure and anatomy of the by which the bird climbs; to say nothing of proboscis itself, we should see in it one of the the use which it makes of it in breaking nuts most curious of all examples of animal mecha- and the hard substances upon which it feeds nism. The disposition of the ringlets and fi- How, therefore, has nature provided for the bres, for the purpose, first, of forming a long opening of this occluded mouth? By making cartilaginous pipe; secondly, of contracting the upper chap moveable, as well as the lower. and lengthening that pipe; thirdly, of turn-In most birds, the upper chap is connected, ing it in every direction at the will of the ani- and makes but one piece, with the skull; but mal; with the superaddition at the end, of a in the parrot, the upper chap is joined to the fleshy production, of about the length and bone of the head by a strong membrane placthickness of a finger, and performing the of-ed on each side of it, which lifts and depresses fice of a finger, so as to pick up a straw from it at pleasure.*

the ground; these properties of the same or gan, taken together, exhibit a specimen, not only of design (which is attested by the ad

V. The spider's web is a compensating con

• Goldsmith's Natural History

trivance. The spider lives upon flies, without | VIII. In another animal, and in another wings to pursue them; a case, one would have part of the animal economy, the same Memoirs throught, of great difficulty, yet provided for, describe a most remarkable substitution. The and provided for by a resource which no stra-reader will remember what we have already tagem, no effort of the animal, could have pro- observed concerning the intestinal canal; that duced, had not both its external and internal its length, so many times exceeding that of the structure been specifically adapted to the ope- body, promotes the extraction of the chyle from ration. the aliment, by giving room for the lacteal vessels to act upon it through agreater 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 alopecia, or sea-fox. 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

VI. In many species of insects, the eye is fixed; and consequently without the power of turning the pupil to the object. This great defect is, however, perfectly compensated; and by a mechanism which we should not suspect. The eye is a multiplying-glass, with a lens looking in every direction and catching every object. By which means, although the orb of the eye be stationary, the field of vision is as ample as that of other animals, and is commanded on every side. When this lattice work was first observed, the multiplicity and minuteness of the surfaces must have added to the surprise of the discovery. Adam teils us, that fourteen hundred of these reticulations have been counted in the two eyes of a drone-route, is conducted to its exit. Here the shortbee.

In other cases the compensation is effected by the number and position of the eyes themselves. The spider has eight eyes, mounted upon different parts of the head; two in front, two in the top of the head, two on each side. These eyes are without motion; but, by their situation, suited to comprehend every view which the wants or safety of the animal rendered it necessary for it to take.

ness of the gut is compensated by the obliquity of the perforation.

IX. But the works of the Deity are known by expedients. Where we should look for absolute destitution; where we can reckon up nothing but wants; some contrivance 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 VII. The Memoirs for the Natural Histo-to the stems, leaves, and fruits of plants, by ry of Animals, published by the French Aca-means of a sticking-plaster. A muscle, which demy, A. D. 1687, furnish us with some cu- might seem, by its helplessness, to lie at the rious particulars in the eye of a chameleon.mercy of every wave that went over it, has Instead of two eyelids, it is covered by an the singular power of spinning strong tendieyelid with a hole in it. This singular struc- nous threads, by which she moors her shell to ture appears to be compensatory, and to an- rocks and timbers. A cockle, on the contraswer to some other singularities in the shape ry, by means of its stiff tongue, works for itof the animal. The neck of the chameleon is self a shelter in the sand. The provisions of inflexible. To make up for this, the eye is so nature extend to cases the most desperate. A prominent, as that more than half of the ball lobster has in its constitution a difficulty so stands out of the head; by means of which great, that one could hardly conjecture beforeextraordinary projection, the pupil of the eye hand how nature would dispose of it. In most can be carried by the muscles in every direc-animals, the skin grows with their growth. tion, and is capable of being pointed towards If, instead of a soft skin, there be a shell, still every object. But then, so unusual an expo-it admits of a gradual enlargement. If the sure of the globe of the eye requires, for its shell, as in the tortoise, consist of several pielubricity and defence, a more than ordinary ces, the accession of substance is made at the protection of eyelid, as well as a more than sutures. Bivalve shells grow bigger by receiv ordinary supply of moisture; yet the motioning an accretion at their edge; it is the same of an eyelid, formed according to the common with spiral shells at their mouth. The simconstruction, would be impeded, as it should plicity of their form admits of this. But the seem, by the convexity of the organ. The lobster's shell being applied to the limbs of the aperture in the lid meets this difficuly. It en- body, as well as to the body itself, allows not ables the animal to keep the principal part of of either of the modes of growth which are the surface of the eye under cover, and to pre- observed to take place in other shells. Its serve it in a due state of humidity without hardness resists expansion; and its complexishutting out the light; or without perform-ty renders it incapable of increasing its size by ing every moment a nictitation, which, it is probable, would be more laborions to this animal than to others.

addition of substance to its edge. How then was the growth of the lobster to be provided for? Was room to he made for it in the old

shell, or was it to be successively fitted with tion. The sheep, deer, and ox tribe, are with. new ones? If a change of shell became neces-out fore-teeth in the upper jaw. These rumi. sary, how was the lobster to extricate himself nate. The horse and ass are furnished with from his present confinement? how was he teeth in the upper jaw, and do not ruminate. to uncase his buckler, or draw his legs out of In the former class, the grass and hay descend his boots? The process, which fishermen have into the stomach, nearly in the state in which observed to take place, is as follows: At cer- they are cropped from the pasture, or gath tain seasons, the shell of the lobster grows soft ered from the bundle. In the stomach, they the animal swells its body; the seams open, are softened by the gastric juice, which in and the claws burst at the joints. When the these animals is unusually copious. Thus shell has thus become loose upon the body, softened and rendered tender, they are returnthe animal makes a second effort, and by a ed a second time to the action of the mouth, tremulous, spasmodic motion, casts it off. In where the grinding teeth complete at their leithis state, the liberated but defenceless fish sure the trituration which is necessary, but retires into holes in the rock. The released which was before left imperfect. I say, the body now suddenly pushes its growth. In trituration which is necessary; for it appears about eight-and-forty hours, a fresh concretion from experiments, that the gastric fluid of of humour upon the surface, i. e. a new shell sheep, for example, has no effect in digesting is formed, adapted in every part to the increas-plants, unless they have been previously mased dimensions of the animal. This wonder- ticated; that it only produces a slight macera. ful mutation is repeated every year. tion, nearly as common water would do in a If there be imputed defects without compen-like degree of heat; but that when once ve. sation, I should suspect that they were defects getables are reduced to pieces by mastication, only in appearance. Thus, the body of the the fluid then exerts upon them its specific sloth has often been reproached for the slow-operation. Its first effect is to soften them, ness of its motions, which has been attributed and to destroy their natural consistency: i to an imperfection in the formation of its then goes on to dissolve them; not sparing limbs. But it ought to be observed, that it is even the toughest parts, such as the nerves of this slowness which alone suspends the voracity the leaves.

of the animal. He fasts during his migration I think it very probable, that the gratifica from one tree to another: and this fast may tion also of the animal is renewed and prolongbe necessary for the relief of his overcharged ed by this faculty. Sheep, deer, and oxen, vessels, as well as to allow time for the con-appear to be in a state of enjoyment whilst coction of the mass of coarse and hard food they are chewing the cud. It is then, perhaps, which he has taken into his stomach. The that they best relish their food. tardiness of his pace seems to have reference II. In birds, the compensation is still more to the capacity of his organs, and to his propensities with respect to food; i. e. is calculated to counteract the effects of repletion.

striking. They have no teeth at all. What have they then to make up for this severe want? I speak of granivorous and herbivorous Or there may be cases, in which a defect is birds; such as common fowls, turkeys, ducks, artificial, and compensated by the very cause geese, pigeons, &c.; for it is concerning these which produces it. Thus the sheep, in the alone that the question need be asked. All domesticated state in which we see it, is des- these are furnished with a peculiar and most titute of the ordinary means of defence or es- powerful muscle, called the gizzard; the in cape; is incapable either of resistance or flight. ner coat of which is fitted up with rough plaits, But this is not so with the wild animal. The which, by a strong friction against one another, natural sheep is swift and active; and if it lose break and grind the hard aliment as effectua!these qualities when it comes under the sub-ly, and by the same mechanic 1 action, as a jection of man, the loss is compensated by his coffee-mill would do. It has been proved by protection. Perhaps there is no species of the most correct experiments, that the gastric quadruped whatever, which suffers so little as juice of these birds will not operate upon the this does from the depredation of animals of

prey.

entire grain; not even when softened by water or macerated in the crop. Therefore, without For the sake of making our meaning better a grinding machine within its body, without understood, we have considered this business the trituration of the gizzard, a chicken would of compensation under certain particularities have starved upon a heap of corn. Yet why of constitutions, in which it appears to be most should a bill and a gizzard go together? Why conspicuous. This view of the subject neces- should a gizzard never be found where there sarily limits the instances to single species of are teeth?

animals. But there are compensations, per- Nor does the gizzard belong to birds as such. haps not less certain, which extend over large A gizzard is not found in birds of prey. Their classes, and to large portions of living na-food requires not to be ground down in a mill. The compensatory contrivance goes no farther I. In quadrupeds, the deficiency of teeth is than the necessity. In both classes of birds usually compensated by the faculty of rumina

ture.

* Spall. Dis. iii. sect. cxl.

however, the digestive organ within the body | But the bodies of animals hold, in their conbears a strict and mechanical relation to the stitution and properties, a close and important external instruments for procuring food. The relation to natures altogether external to their soft membranous stomach accompanies a hook-own to inanimate substances, and to the speed notched beak: short, muscular legs; strong, cific qualities of these; e. g. they hold a strict sharp, crooked talons: the cartilaginous sto- relation to the ELEMENTS by which they are mach attends that conformation of bill and toes, surrounded. which restrains the bird to the picking of seeds, or the cropping of plants.

I. Can it be doubted, whether the wings of birds bear a relation to air, and the fins of fish III. But to proceed with our compensations." to water? They are instruments of motion, A very numerous and comprehensive tribe of severally suited to the properties of the meterrestrial animals are entirely without feet; dium in which the motion is to be performed: yet locomotive; and in a very considerable de- which properties are different. Was not this gree swift in their motion. How is the want difference contemplated, when the instruments of feet compensated? It is done by the dispo-were differently constituted?

sition of the muscles and fibres of the trunk. II. The structure of the animal car depends In consequence of the just collocation, and by for its use, not simply upon being surrounded ineans of the joint action of longitudinal and by a fluid, but upon the specific nature of that annular fibres, that is to say, of strings and fluid. Every fluid would not serve: its par rings, the body and train of reptiles are capa- ticles must repel one another; it must form an ble of being reciprocally shortened and length-elastic medium: for it is by the successive ened, drawn up and stretched out. The result pulses of such a medium, that the undulations of this action is a progressive, and, in some excited by the surrounding body are carried to cases, a rapid movement of the whole body, in the organ; that a communication is formed any direction to which the will of the animal between the object and the sense; which must determines it. The meanest creature is a col-be done, before the internal machinery of the lection of wonders. The play of the rings in ear, subtile as it is, can act at all. an earth-worm, as it crawls; the undulatory III. The organs of voice, and respiration, motion propagated along the body; the beards are, no less than the ear, indebted, for the suc or prickles with which the annuli are armed, cess of their operation, to the peculiar qualities and which the animal can either shut up close of the fluid in which the animal is immersed. to its body, or let out to lay hold of the rough- They, therefore, as well as the ear, are con ness of the surface upon which it creeps; and stituted upon the supposition of such a fluid, the power arising from all these, of changing i. e. of a fluid with such particular properties its place and position, affords, when compared being always present. Change the properties with the provisions for motion in other ani- of the fluid, and the organ cannot act ; change mals, proofs of new and appropriate mechan- the organ, and the properties of the fluid would ism Suppose that we had never seen an ani- be lost. The structure, therefore, of our ormal move upon the ground without feet, and gans, and the properties of our atmosphere, that the problem was,-Muscular action, i. e. are made for one another. Nor does it alter reciprocal contraction and relaxation being the relation, whether you allege the organ te given, to describe how such an animal might be made for the element, (which seems the be constructed, capable of voluntarily chang- most natural way of considering it,) or the ing place. Something, perhaps, like the or- element as prepared for the organ. ganisation of reptiles, might have been hit IV. But there is another fluid with which upon by the ingenuity of an artist: or might we have to do; with properties of its own. have been exhibited in an automaton, by the with laws of acting, and of being acted upon, combination of springs, spiral wires, and ring- totally different from those of air and water: lets: but to the solution of the problem would and that is light. To this new, this singular not be denied, surely, the praise of invention element; to qualities perfectly peculiar, perand of successful thought: least of all could it ever be questioned, whether intelligence had been employed about it, or not.

CHAPTER XVII.

fectly distinct, and remote from the qualities of any other substance with which we are acquainted, an organ is adapted, an instrument is correctly adjusted, not less peculiar amongst the parts of the body, not less singular in its form, and in the substance of which it is com❤ posed, not less remote from the materials, the

THE RELATION OF ANIMATED BODIES TO model, and the analogy of any other part of

INANIMATE NATURE.

We have already considered relation, and under different views; but it was the relation of parts to parts, of the parts of an animal to other parts of the same animal, or of another individual of the same species.

the animal frame, than the element to which it relates, is specific amidst the substances with which we converse. If this does not prove appropriation, I desire to know what would prove it.

Yet the element of light and the organ of vision, however related in their office and use.