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perfect insect, others do not bear the slightest resemblance to it. The difference in the former class consists usually in proportion of parts, want of wings, or such like characters. In the latter the characters are so different from those of the perfect insect, as not, in any degree, to lead a casual observer ever to conclude that they were the same. This difference will be sufficiently indicated, for our present purpose, by the simple announcement, that it is that between a grub and a fly, a caterpillar and a butterfly.
As it consists with neither our time nor space to attempt anything like even an outline of insect history, we content ourselves with the statement of one or two facts, calculated to inspire an interest in the subject.
In a former paper we narrated the history of the transformation of a dragon-fly. The larva of this fly presents, perhaps, the most striking instance of design, in the construction of its under-lip, so as to fit it for seizing its prey. It is thus described by Kirby and Spence:
- In other larvæ this part is usually small and inconspicuous, and seems merely for retaining the food, and assisting in its deglutition; but in these it is by far the largest organ of the mouth, which, when closed, it entirely conceals; and it not only retains, but actually seizes the animal's prey, by means of a very singular pair of jaws, with which it is furnished. Conceive your under-lip (to have recourse, as Reaumur on another occasion, to such a comparison) to be horny instead of fleshy, and to be elongated perpendicularly downwards, so as to wrap over your chin and extend to its bottom,—that this elongation is there expanded into a triangular convex plate, attached to it by a joint, so as to bend upwards again and fold over the face, as high as the nose, concealing not only the chin and the firstmentioned elongation, but the mouth and part of the cheeks ;-conceive, moreover, that to the end of this last-mentioned plate are fixed two other convex ones, so broad as to cover the whole nose and temples,—that these can open at pleasure, transversely, like a pair of jaws, so as to expose the nose and mouth, and that their inner edges, where they meet, are cut into numerous sharp teeth or spines, or armed with one or more long and sharp claws-you will then have as accurate an idea as my powers of description can give, of the strange conformation of the under-lip in the larvæ of the tribe of Libellulina, which conceals the mouth and face precisely as I have supposed a similar construction of your lip would do yours. You will probably admit that your own visage would present an appearance not very engaging while concealed by such a mask ; but it would strike still more awe into the spectators were they to see you first open the two upper jaw-like plates, which would project from each temple like the blinders of a horse ; and next having, by means of the joint at your chin, let down the whole apparatus, and uncovered your face, employ them in seizing any food that presented itself, and conveying it to your mouth. Yet this procedure is that adopted by the larvæ provided with this strange organ. While it is at rest, it applies close to and covers the face. When the insects would make use of it, they unfold it like an arm, catch the prey at which they
aim by means of the mandibuliform (jaw-like) plates, and then partly refold it, so as to hold the prey to the mouth in a convenient position for the operation of the two pair of jaws with which they are provided. You will admire the wisdom of this admirable contrivance, when you reflect that these larvæ are not fitted to pursue their prey with rapidity, like most predaceous animals ; but that they steal upon them, as De Geer observes, as a cat does upon a bird, very slowly, and as if they counted their steps, and then, by a sudden evolution of this machine, take them as it were by surprise, when they think themselves safe.' These animals are found in almost every ditch, so that the curious construction just described may be easily examined.
Other points in the construction of larvæ are equally interesting. For these we must refer to works on the subject. One peculiarity, however, we must not overlook-their changes of skin. Some larvæ change their skins four, some five or eight, some nine, and some even ten times. The caterpillar of the common tiger moth changes generally ten times. Some now (May) in our possession, and which have been alive all winter, have changed their skins twice since we got them in April.
A day or two previous to each change of its skin, the larva ceases eating altogether: it becomes languid and feeble, its beautiful colours fade, and it seeks for a retreat in which it can undergo this important and sometimes dangerous and even fatal operation in security. Here, either fixing itself by its legs to the surface on which it rests, or, as is the case with some caterpillars, by its prolegs, to a slight web spun for this purpose, it turns or twists its body in various directions, and alternately swells and contracts its different segments. The object of these motions and contortions seems to be, to separate the exterior skin, now come dry and rigid, from the new one just below it. After continuing these operations for some hours, resting at intervals without motion, as if exhausted by their violence, the critical moment arrives; the skin splits on the back, in consequence of the still more violent swelling of the second or third segment; the opening thus made is speedily increased by a succession of swellings and contractions of the remaining segments; even the head itself often divides into three triangular pieces, and the enclosed larva by degrees withdraws itself from its old skin.' Such is the usual though not universal way in which this operation is performed. Everything is changed, hairs, skull, eyes, antennae, palpi, jaws, and legs. But this is not all. Swammerdam says, of the grub of a certain beetle, 'Nothing in all nature is, in my opinion, a more wonderful sight than the change of skin in these and other the like worms. This matter, therefore, deserves the greatest consideration, and is worthy to be called a specimen of nature's miracles; for it is not the external skin only that these worms cast, like serpents, but the throat and a part of the stomach ; and even the inward surface of the great gut changes its skin at the same time. But this is not the whole of these wonders; for at the same time some hundreds of pulmonary pipes within the body of the worm cast also each its delicate and tender skin. These several skins are afterwards collected into eighteen thicker, and as it were compounded ropes, nine on each side of the body, which, when the skin is cast, slip gently, and by degrees, from within the body through the eighteen apertures or orifices of the pulmonary tubes, before described, having their tops or ends directed upwards towards the head. Two other branches of the pulmonary pipes, that are smaller and have no points of respiration, cast a skin likewise.' "The larva which has undergone this painful process is at first extremely weak, and its parts are soft and tender. Its colour, too, is usually paler than before, and its markings indistinct, until their tints have been enlivened by exposure to the air, when they become more fresh, vivid, and beautiful to appearance than ever. When a few meals have invigorated its languid powers, the renovated animal makes up for its long abstinence by eating with double voracity.'
When the requisite amount of food has been eaten, the requisite number of skins cast, and the requisite growth attained, the larvæ begin preparing to enter the third state—that of pupa. Some remain where they happen to be; others seek a place of security in which to pass the helpless period of their new state. Some creep into chinks in walls or wood; others cover themselves with dead leaves, moss, &c. A great many betake themselves to the earth, and burrow in it. Some that pass the larva state in the water, seek the shore. A large section suspend themselves to leaves, or twigs, or stones by a silken thread; and a very numerous tribe shut themselves completely up in cocoons or cases.
To describe the beautiful manæuvres by which this suspension is attained, or these cocoons formed, would occupy more space than our whole series of articles may extend to, but would prove, perhaps, not the least interesting subject of research. We, in the meantime, however, pass on to the third state, our notice of which will be very limited. To include all insects, this state has been defined to be that intervening between the larva and imago (or perfect insect), in which the parts and organs of the perfect insect-though in few cases fully developed, are prepared and fitted for their final and complete development in the last-mentioned state, and in which the majority of these animals are incapable of locomotion or of taking food. As in the last state, so also in this, different tribes differ in the characteristics and conditions of their pupa state. Some are scarcely to be distinguished from their former larva-look, or from their perfect state; others, again, are entirely different from any former or future condition. These latter we know commonly by the name chrysalises, which was given to them on account of the gilded or golden appearance which some of them present. In this state they remain for a longer or shorter period of days, weeks, months, and even years. In one instance, out of thirty-six eggs laid by one moth, and all of which went into the pupa state together, twelve came out at the usual season, twelve more in the following one, and the remaining twelve did not come out till the third season, when, however, they were equally perfect with the others.
The formation of the cocoons or cases is not more curious than the different modes by which the insects extricate themselves from them, when they have attained their perfect state. We once kept several caterpillars of the puss moth, and in process of time saw them pass into the pupa state. They constructed for themselves chambers against the side of the glass in which they were kept, forming their walls with wood-dust and glne, and making them of great strength. To the ordinary observer it might have seemed impossible that a moth, the emblem of frailty, could break up such an imprisoning wall and come forth. Nevertheless in due time forth they came. Each moth is provided with a bag of acid. "The contents of this she pours out as soon as she has forced her head through the skin of the chrysalis, and upon the opposite side of the cocoon. The acid instantly acts upon the gum, loosens the cohesion of the grains of wood, and a gentle effort suffices to push down what was a minute ago so strong a barrier !'
We were furnished a few weeks ago, through the kindness of a friend, with some chrysalises of the common cabbage butterfly, and some caterpillars of the tiger moths, along with other insect specimens. After feeding voraciously for some time, and casting their skins once or twice, the caterpillars have now built themselves a large and strong chamber, cutting the hair from their own bodies to line it, and strengthening it with the stripped midribs of the dandelion leaves on which they had been feeding. These are fastened together with threads woven by the insects, and the interstices filled up with gum. Within this they have now gone into the pupa state, from which we look for their coming forth moths in the course of a few weeks more.
The chrysalises of the cabbage butterfly must be well known. They may be seen almost anywhere, attached to old walls, and beneath the eaves of houses. They look to the passer-by like mere bits of lime-a provision of colour no doubt intended for their security. We had them lying in a box, the top of which was covered with glass, and were in hopes we might be fortunate enough to see them change. The first one, however, came out much sooner than we expected, and early in the morning. The other was some weeks later, and we feared that the insect had died. This fear increased when we noticed the chrysalis growing darker and darker, till we discovered this to be the symptom of change. On reading this one evening, we thought of looking at our prisoner to see how he fared, but something came in the way, and we did not. In the morning a fine large butterfly, with wings two inches across, was fluttering in the box. In the one instance the case was considerably broken, but in the other only a neat small slit had been made at one end. Both the insects had expanded into perfect beauty before we observed that they had come forth. When they first come out, however, their wings are small and of a dull colour, and their parts soft and languid. The process of expansion is, however, rapid. It is thus described by a writer who witnessed it in the case of a rare butterfly which he reared from a pupa :
— With great care,' says he, “I placed it on my arm, where it kept pacing about for the space of more than an hour. To observe how gradual and yet how rapid was the development of the parts and organs, and particularly of the wings, and the perfect coming forth of the colours and spots as the sun gave vigour to it, was a most interesting spectacle. At first it was unable to elevate or even move its wings ; but in proportion as the ærial or other fluid was forced, by the motions of its trunk, into their nervures, their numerous corrugations and folds gradually yielded to the action, till they had gained their greatest extent, and the film between all the nervures became tense. The ocilli, and spots, and bars, which appeared at first as but germs or rudiments of what they were to be, grew with the growing wing, and shone forth upon its complete expansion in full magnitude and beauty,'—and so it soars away upon the errand of its life.
We must now bid adieu to these interesting themes. We have collected our illustrations from the works of those who have deeply studied what they wrote about; and we have added some experiences of our own, to show that what we recommend as an interesting pursuit has had rewards as well as charms for ourselves. One of the thousand lessons spread out before the student of nature has been beautifully recorded by the poet, in the lines we have placed at the head of this paper. For the rest we may say, open the book and read for yourselves. Accept, however, this caution, ere we part: Beware of putting Nature in the place of God. A betrayer of the Sabbath, and an advocate of its desecration, has lately said, that he communed in spirit with his God amid the scenes of nature, and his prayers ascended in unison with the rustling of the leaves and the carols of the feathered choir. There is an idolatry of Nature, which is actual infidelity. What is the difference between geology and theology ? we heard asked the other day. "The difference between earth and heaven,' was the reply. The question and answer relate equally to all natural science on the one hand, and all revealed truth on the other.
Both are of God; and both, rightly employed, subserve the same end. But he greatly mistakes both who accepts the one, and discards the other. For if it is true, on the one hand, that the invisible things of God, from the creation of the world, are clearly seen, being understood by the things that are made,'—and so the doctrines of theology receive illustration from the discoveries of science,—much more is it so, on the other hand, that of too many of the disciples of science it may be said, Ye do err, not knowing the scriptures.' While bible theology is independent of natural science, natural science proves dangerous when it assumes a position independent of the scriptures of truth. The first is crippled and shorn of some of its rays, when deprived of the other ; but the second is poison, and not food, when unrectified by the true word of prophecy. When, therefore, you pursue these studies, towards which we have sought to turn you, let it be in the way of complying with the advice of the French philosopher, who said, “It is Bible in hand that we ought to enter the august temple of Nature, that we may recognise aright the voice of the Creator.