skin, now converted into a leathern case, it undergoes its transformations, which have been minutely traced by Reaumur, but which I shall not enumerate, as this would lead into a somewhat tedious detail. We are so apt to consider the processes of insect transformation as insignificant, merely on account of the smallness of the animal, that it is sometimes desirable to suppose a case in which bulk would appear to add to their importance. Mr Rennie has, in the present instance, successfully availed himself of this device :— "Were such an extraordinary transformation as this," says he, "to happen to one of the larger animals, it would be held forth as altogether miraculous. Were a lion or an elephant, for example, to coil itself up into a ball, compressing its skin into twice the thickness, and half the extent, while it remained uniform in shape, and without joinings or openings; and, at the same time, were it entirely to separate its whole body from this skin, and lie within it as a kernel does in a nut, or a chick in an egg, throwing off its now useless tusks into a corner, and then, after a space, should it acquire wings, break through the envelope, and take its flight through the air, there would be no bounds to our admiration. Yet the very same circumstances, in miniature, take place every day during summer, almost under the eye of every individual, in the case of the blow-fly, without attracting the attention of one person in a million." " Were we to follow up this idea, by supposing the various tribes of the insect world magnified to the dimensions of man, and the vertebrated animals, with which he is immediately associated, we should acquire more distinct views of their relative powers; but what a scene of wonders would be disclosed to our view. It would be pleasant to give way to our fancy in peopling the world with the monsters-strange and diverse, which would then meet us on every side. Looking only to one of the * Insect Transformations, p. 282. species we have been considering, we should see a creature large and fearful as a crocodile, for a time consuming everything before it with the voracity of a hundred cattle, but presently becoming sick and refusing to eat; and then climbing the highest trees, spinning ropes from its bowels, weaving a net, and hanging itself up by the feet to the winds of heaven; and then again bursting its natural covering, coming forth to the open air, naked and in a new shape, and, in resuming its position, discovering a tact and agility which neither man nor quadruped could equal; once more we would observe this wonderful animal voluntarily suspended at the giddy height it had first assumed, and remaining exposed to the changing season till a new metamorphosis took place. Again it bursts its external covering; and now it comes forth a glorious being, shining with sapphire, emeralds, and gold, expanding its painted wings in the sun, and soaring joyously through the yielding air. Such would be the history of one class of existences; and a hundred more, equally surprising and extraordinary, would meet our view on every side. But instead of pursuing this train, let us look at some of the faculties and operations of the insect tribes as compared with those of higher species. The flea can draw seventy or eighty times its own weight,* and it can leap to the distance of 200 times its own length. It is, therefore, immensely stronger than a horse; and were a man able to equal the agility of this little animal, he could leap between 300 and 400 yards. But the cuckoo-spit froghopper has still greater elasticity of limbs, being able to leap more than 250 times its own * Many wonderful exhibitions of the strength of the flea have been made, one of the first of which was in Cox's museum, about sixty or seventy years ago. Mr Boverich, a London watchmaker, constructed a minute landau, which opened and shut by springs, with the figures of six horses harnessed to it, and of a coachman on the box, a dog between his legs, four persons inside, two footmen behind it, and a postilion riding on one of the four horses, which were all easily dragged along by a single flea. Goldsmith remarks, that the feats of Samson would not, to a community of fleas, appear to be at all miraculous. length; and, to vie with this, a man of ordinary stature should vault through the air to the distance of a quarter of a mile! It has been remarked, that according to a similar mode of comparison, a cockchaffer is six times stronger than a horse; and Linnæus observes, that if an elephant were as strong in proportion as a stag-beetle, it would be able to tear up rocks and level mountains. The architecture of insects is not less remarkable than their strength and agility. It has been said, that the community of white ants erects a building 500 times their own height. Were our houses built on the same proportions, they would be twelve or fifteen times higher than the London Monument, and four or five times higher than the Pyramids of Egypt, with corresponding dimensions at the base: to such buildings St Paul's would be but as a bee-hive! "The minute observation," says Mr Rennie, in stating comparisons of this kind, “by which such unexpected facts are discovered, has in all ages been a fertile source of ridicule for the wits, from the time when Aristophanes in his 'Clouds' introduced Socrates measuring the leap of a flea, up to Peter Pindar's lampoon on Sir Joseph Banks and the Emperor butterfly.' To all such flippant wit, we have merely to retort the question of the Abbé de la Pluche,— If the Deity thought insects worthy of his divine skill in forming them, ought we to consider them beneath our notice?'"* SIXTH WEEK-WEDNESDAY. INSECT TRANSFORMATIONS.-THEIR IMAGO OR PERFECT STATE. WHILE the insect is in its chrysalis state, the future fly is gradually formed and developed, and at last it again emerges to the light of day, by throwing off its * Insect Transformations, p. 180. external covering. The manner in which this is effected is far from uniform, but is suited, in each species, with remarkable care, to its individual peculiarities. The very singular manner in which the aquatic pupa of the gnat disengages itself on the surface of the water, making use of its coffin, during the operation, as a boat, has already been described.* One other instance may be mentioned, premising that most insects liberate themselves without external aid, being assisted by various prospective contrivances, among which may be named the swelling of their bodies, which breaks their coverings at some convenient place, and enables them to make use of their natural conformation in emerging, their bodies being generally composed of rings, which can be contracted or expanded at pleasure. The case I select is that of the ant; and I do so, because it affords an example of an insect which, being incapable of extricating itself from its pupa-shell, is indebted for assistance, in this last change, to the already liberated inhabitants of the same nest. The younger Huber, in describing these pupæ, which are inclosed in a tissue spun by themselves, says, "they have scarcely the power of moving; their covering is of too compact a texture, and formed of too strong a silk, to allow of their tearing it, without the assistance of the workers. But how do these indefatigable attendants ascertain the proper moment for this process? If they possessed the faculty of hearing, we might imagine they knew the fit time, from some noise produced in the interior of the prison, by the insects whose development is commenced; but there is no indication favouring this opinion; it is probable they have a knowledge of it from some slight movements that take place within, which they ascertain through the medium of their antennæ; for these organs are endowed with a sensibility of which it would be difficult to form a just idea." The following is the manner in which, as described Spring," p. 130. by this author, the ants were observed to proceed :-" I noticed three or four, mounted on one of these cocoons, endeavouring to open it with their teeth, at that extremity answering to the head of the pupa. They began to thin it, by tearing away some threads of silk, where they wished to pierce it; and, at length, by dint of pinching and biting this tissue, so extremely difficult to break, they formed in it a vast number of apertures. They afterward attempted to enlarge these openings by tearing and drawing away the silk; but these efforts proving ineffectual, they passed one of their mandibles into the cocoon, through the apertures they had formed, and, by cutting each thread, one after the other, with great patience, at length effected a passage of a line in diameter in the superior part of the web." They afterward cut out a portion in the longitudinal direction of the cocoon, with their teeth alone, employing them as we employ scissors; and, as the work of extrication is a task of great labour, the ants relieved one another, till at last they were enabled to draw out the insect from its imprisonment. Their toil, however, was not yet completed; for the young ant, being enwrapped in another membrane, "could neither fly nor walk, nor, without difficulty, stand." Of this satin-like investment it was likewise stripped by the indefatigable assiduity of its followers; and, to crown all this care, which maternal attentions alone could equal, the first object of these kind guardians, was to supply the craving appetite of their young charge with necessary food.* The providential intention of this arrangement is remarkable. The grub of the ant might doubtless have been formed with the power of extricating itself from its cocoon as well as the grubs of other insects; but, as it is destined to live in a community, all the members of which are united together for the common welfare, it seems to have been designed, by the instinct that has been noticed, and the necessity which required it, to *Huber on Ants, p. 88. |