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that these animals exhibit this persistency of imitation; their larvæ are, if less universally, not less strangely and successfully metamorphosed. Look at the larva of the peacock-moth, and see how exactly the general ground-colour harmonises with that of the young buds of heather on which it feeds, and how closely the pink spots with which it is decorated corre- spond with the flowers and flower-buds. I should say that one half of the caterpillars of moths and butterflies are green, closely resembling the hue of the leaf on which they feed; and when a part of the body only is exposed to view, the resemblance is often restricted to that part, as may be seen in the larva of one of our tiger-beetles (Cicindela campestris), which lives in a hole, from which its head and thorax alone protrude; and these are of the same green as the perfect insect, while the rest of the body is of the usual whitish-yellow of a grub. There are few gardeners who have not in their time been surprised to find that they have taken a fleshy caterpillar between their fingers when they have thought to break off a dead twig; the geometers, or loopers, having the strange habit of stretching themselves out stiff and stark like a twig on the shrub or tree on which they feed; and as, like a vast number of the insect tribes, each is pretty much confined to one plant, or family of plants, for its food, we find that the resemblance is carried out to the extent of making the insect resemble the twigs of the particular plant on which it feeds, and, to add to the deception, is embossed at suitable intervals with one or two eminences, made to imitate the buds on the side of the twig.

Among the denizens of the waters we certainly do not find so many instances of disguise; still we are by no means without examples. In one small crustacean, Caprella phasma, which in these days of tanks and vivaria must be familiar to many of my readers, exactly the same habit is repeated which we have found among the loopers. It is a linear animal, about half an inch in length, semi-transparent, and of the same colour and consistency as a zoophyte, such as an Antennaria or Plumularia. If put alive into a tank containing a bunch of these zoophytes, it fixes itself among them by its hind legs; and stretching out its body, and every limb and joint, as stiff and rigid as iron, it requires a careful examination to be able

to detect it. Among the marine annelides, too, we find the hue of the green, purple, and red sea-weeds exactly reproduced in Nemertis and Planaria, &c. The mollusca do not furnish such striking instances of resemblance to particular objects— › the amount of concealment shown in the sea-shells being chiefly confined to veiling the glowing colours of the shell under a coarse yellow epidermis, which corresponds in colour. to the bottom of the sea on which they lie. Not that we are absolutely without instances of the place of life correspondingly affecting the colour, as for instance in the Patella pellucida and the Patella cærulea, the former of which is dark, and of the colour of the frond of the large Laminaria, on which only it is found; and the latter, which is confined to the stalk, is paler, and of its hue:—an instance, however, on which I put no weight, because it may be pled that both the P. cærulea and P. pellucida are the same species, modified by food; and where we have an embarras des richesses in the choice of unchallengable illustrations in other classes, it is unnecessary to burden ourselves with the defence of doubtful examples in this. Of the lower animals, the Actinic furnish some good examples of disguise. I can hardly suggest a more perfect one than Actinia troglodytes in a sandy pool, its tentacles being so exactly marbled like a sandy bottom, that the pool may be paved with them all expanded, and yet the casual observer-ay, more, the attentive but uninstructed eye-never see one!

The illustrations which I have thus far made use of are drawn from animals exhibiting these disguises permanently, and without variation; but there is another class of imitators which I must not pass over, those which have as it were more than one disguise in their wardrobe-one for summer and another for winter; as, for instance, the Alpine hare, the stoat or ermine, the ptarmigan, some grouse, &c.; and this a disguise which is made more or less perfect according to the severity of the winter, which is the accompaniment, I shall not say cause, of the change; for in species which constantly inhabit snowy regions, we find that the farther north we go the whiter they become-in the extreme north sometimes becoming replaced by a different species, wholly and perma

nently white; as in the case of the Arctic hare taking the place of the Alpine hare-both white, but the Arctic of trebledistilled purity compared with the Alpine. In other instances, the change is not dependent upon the seasons. In fish, it is a familiar instance that the colour varies with the colour of the waters. The trout in clear streams and lakes is silvery white; in peaty waters, dark. The Lochnagar trout, for example, where the waters are dark and peaty, is nearly black on the back. The flounder, which exactly resembles the ground over which it hovers, changes its hue in an amazingly short time, on passing from one bank to another of a different colour. Anglers who use minnows for bait know that if they are put in a light-coloured vessel they become pale; and if they be transferred to a dark one, they will become dark in the space of an hour. A similar though more permanent alteration takes place in various birds. Colquhoun, in his entertaining volume, the "Moor and the Loch," says, "In the low corn districts, such as Lanarkshire, Renfrewshire, and the Border counties, the grouse are of a very light brown, borrowing a tint from the stubbles on which they delight to feed." Forty or fifty are often taken at a time (by snares) during the period between the corn being cut and carried. All these birds are so light in their colour as more nearly to resemble partridges" (p. 112). And we find the converse of this to take place in partridges. "These moor partridges," he says, "which spend much of their time in the heather, are of a darker colour than those of the Lowlands." (Foot-note, p. 113.)

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Do any such resemblances as we have been speaking of obtain in plants? They are comparatively few certainly; but in some of the lower plants they certainly do exist. The crusted lichen often bears a close resemblance to the rock on which it is found, and the olive-tinted fucus to the wet reefs which it covers; but the examples are few in plants, and, what is not to be overlooked, we can see no purpose for their exist

ence.

The hasty glance which we have thus cast over animated creation sufficiently shows three things-first, that the most perfect imitations of inanimate objects do occur; second, that this is not a rare or exceptional thing, but one found

in every class of animals, and in some found so frequently as to be the rule, and the want of it the exception; and, lastly, that so apparent is the means to the end, that it is plain that there is a purpose in it, and that that purpose is the concealment of the animals that bear the disguise. Now, how does this come about? Is it the result of any general law; or must we be satisfied to say that these disguises have been given by Providence for the purposes of the preservation of His creatures, and rest there? I apprehend not. This is not the mode in which the Creator carries out His ends. It is indeed very easy to say, that a special exercise of the creative power has been used in these disguises in every separate instance; but if it is so, it is different from all we know of the other workings of Providence. A great law in all of them is set in motion, which, while regardless apparently of minor details and individual interests, yet, by its general working, most efficiently provides for them. Through the operation of such laws elsewhere, we see everything harmoniously and necessarily assuming its place and its form; and we cannot doubt that such a great law also exists in this matter.

What is this law? I cannot tell; but it has occurred to me, that the law may perhaps be found somewhere in the direction of an analogous force to the great law of attraction, otherwise called gravitation. Like draws to like, or like begets like. We have seen that in all the instances to which I have referred the external appearance of the animal bears definite relation to the appearance of the soil on which it lives, or the objects which surround it. It would appear as if there were a genius loci, whose subtle and pervading essence spread itself around, penetrating and impregnating the denizens of the place with its facies-possibly only affecting some, the conditions of whose entry on existence render them more liable to receive its impression than others; more probably affecting all, some more and some less. How this mysterious influence may operate, it may be bootless to inquire; but is it unphilosophical, or inconsistent with the simplicity and grandeur of nature, to suppose that one great idea should contain the elements of the laws which regulate all the different constituent parts of the created world? that as by attraction the material

particles forming the solid globe gravitate to each other-as by the action of chemical affinities a like law regulates their intermixture-so a law of attraction should operate in the immaterial world of thought, and influence the phenomena of organic creation?

Assuming, then, as I think we are entitled to do, that some such law does exist, it will not be an unfair test of its truth to inquire whether its operation, like that of all other such laws, extends to all alike; whether its influence is extended both over the just and the unjust, over the rapacious and the inoffensive; or if it has only a partial bearing, confining itself to the weak and the defenceless, as a means of escape, in the absence of means of defence. So far as this goes, it bears the test sufficiently well. The crocodile receives the impress of its laws as well as the chameleon; the Polar bear or Arctic fox as well as the Arctic hare; the Mantis, which preys on other insects, as well as the leaf insect, which feeds on leaves. In the one case, the deception is applied for offence; in the other, for defence. And if we remember that the numbers of those preyed upon must necessarily infinitely preponderate over those which prey upon them, we shall not be surprised at a much greater number of creatures using the disguise for protection than for offence.

Another test which may be applied is more difficult of answer. Looking at it as a law, ought it not to operate by itself, independent of assistance from the animal itself;—that is, if an animal assumes a disguise, ought not the disguise to be complete, pure and simple, without the aid of contrivance. or trick on the part of the animal? A beetle, for instance, is exactly like a pellet of earth or a seed, but only so when its. limbs are all contracted and placed close to its body. In addition to the resemblance, we must have here the instinct of the animal to throw itself into its proper attitude to produce the disguise. True, the natural instinct of fear leads it to shrink into itself; and we may look upon the resemblance as merely an accidental quality which is brought into play by this instinct. But this hardly seems to meet the difficulty. Two concurrent conditions are needed to produce one effect; and we can scarcely hold that the same law which in other

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