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nishes matter for one thread. The spinning instrument, as is evident when viewed by the microscope, unites the two threads into one. Thus a thread of silk, which has the appearance of being single, is in reality double, and spun with great dexterity. Some writers, who delight in the marvellous, ascribe foresight to the silk-worm in spinning its cod. The silk-worm, it must be acknowledged, acts as if it foresaw the approaching event. But the truth is, that, when the animal has acquired its full growth, its reservoirs of silk are completely filled. It then seems to be strongly stimulated to evacuate this glutinous matter. Its different movements and attitudes, while discharging the silk, produce those oval bundles which clothe and ornament vast numbers of the human species.

Another species of caterpillar constructs its cod in the form of a boat with the keel uppermost; but it consists not entirely of pure silk. The animal, with its teeth, detaches small triangular pieces of bark from a bush or tree. These pieces of bark it pastes upon its body by means of a glutinous or silky substance, and they constitute a principal part of its cod.

Another species works also in wood, though not with equal art as the former. Its cod is composed entirely of small irregular fragments of dried wood. These fragments the animal has the address to unite together, and to form of them a kind of box which covers and defends its whole body. It accomplishes this purpose by moistening, for some moments, the pieces of wood in its mouth, and then attaches them to each other by a glutinous substance. Of this mixture the caterpillar forms a cod, the solidity of which is nearly equal to that of wood.

The most solitary of all insects are those which live in the internal parts of fruits. Many of them

which affords them both nourishment and a safe retreat. They dig cavities in the fruit, which some of them either line with silk, or spin cods. Others leave the fruit, and retire to be transformed in the earth.

The metamorphosis of insects has been regarded as a sudden operation, because they often burst their shell or silky covering quickly, and immediately appear furnished with wings. But, by more attentive observation, it has been discovered, that the transformation of caterpillars is a gradual process from the moment the animals are hatched till they arrive at a state of perfection. Why, it may be asked, do caterpillars so frequently cast their skins? The new skin, and other organs, were lodged under the old ones, as in many tubes or cases, and the animal retires from these cases, because they have become too strait. The reality of these encasements has been demonstrated by a simple experiment. When about to molt or cast its skin, if the foremost legs of a caterpillar are cut off, the animal comes out of the old skin deprived of these legs. From this fact, Reaumur conjectured, that the chrysalis might be thus encased, and concealed under the last skin of the caterpillar. He discovered that the chrysalis, or rather the butterfly itself, was inclosed in the body of the caterpillar. The proboscis, the antennæ, the limbs, and the wings of the fly, are so nicely folded up, that they occupy a small space only under the first two rings of the caterpillar. In the first six limbs of the caterpillar are encased the six limbs of the butterfly. Even the eggs of the butterfly have been discovered in the caterpillar long before its transformation.

From these facts it appears, that the transforma tion of insects is only the throwing off external and temporary coverings, and not an alteration of

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the original form. Caterpillars may be considered as analogous to the foetuses of men and of quadrupeds. They live and receive nourishment in envelopes till they acquire such a degree of perfection as enables them to support the situation to which they are ultimately destined by Nature'.

No. XXXVI.

ON TRANSFORMATION IN GENERAL
Omnia transformant sese in miracula rerum.

VIRGIL.

From form to form they pass in wondrous change.

The transformation of caterpillars into winged insects has long excited our admiration. But transformation is not confined to them: all animals, without exception, undergo changes in their structure, mode of existence, and external appearances. Mankind, from their embryo state to their final dissolution, assume many different forms. With respect to an infant, immediately after birth, it is observable to all, that its form, its symmetry, and its organs, are by no means complete. The head, for some time, is disproportionally large; the hands and feet are not properly shaped; the hair is short and scanty; and no teeth appear. In a few months, however the symmetry of all the parts is evidently improved, and the teeth begin to

For more on this subject, consult Lesser's InsectoTheology, by Lyonet, Svo. Lond. 1799, a highly curious

shoot. The growth of the whole body, and the strength and beauty of its form, gradually advance to perfection till the sixth or seventh year, when another change takes place. At this period, the first set of teeth are shed, and are replaced by new ones. From boyhood to puberty, the size of the body, and of its different members, increases. When the age of puberty arrives, several important changes are produced. From this period, to the age of twenty-five or thirty, the muscles swell, their interstices are filled with fat, the parts bear a proper proportion to each other, and man may now be considered as a perfect animal. In this state of perfection and vigour, he generally remains till he reaches his fiftieth year. Then a new, but a gradual change, begins to appear. From the fiftieth year to the age of seventy or eighty, the powers of the body decline in strength and activity. The muscles lose their spring and their force; the vigour of manhood is no longer felt; and the decrepitude of old age is succeeded by death, its unavoidable consequence.

The mind of man undergoes changes as well as is body. The taste, appetites, and dispositions, are in perpetual fluctuation. How different is the taste of a child from that of a man! Fond of gewgaws and of trifling amusements, children frolic away their time without much reflection. When advancing toward puberty, their dispositions and desires suffer a gradual mutation. New instincts are unfolded, and a sense of propriety begins to 'be perceived. They despise their former occupations and amusements; and different species of objects solicit and obtain their attention. Their powers of reflection are now considerably augmented; and both sexes acquire a modesty and a shyness with regard to each other. This awkward, but natural bashfulness, by the intercourse of so

ciety, as well as by the impulses of nature, vanishes soon after puberty, when the state of manhood commences. From this period, to the age of twenty-five or thirty, men's minds assume a bold, enterprising, and active tone. They engage in the business of life, look forward to futurity, and have a desire of marrying, and of establishing families. All the social appetites are in vigour; solid and manly friendships are formed; and man goes on for some time to enjoy every kind of happiness which his nature is capable of affording. At fifty or sixty, the mental powers, in general, like those of the body, begin to decline, till feeble old age arrives, and death terminates the scene.

With regard, to quadrupeds, both before and after birth, they undergo similar, and many of them greater changes of form than those of the human species. Their mental powers, likewise, their dispositions and manners, as well as the objects of their attention, vary according to the different stages of their existence. Many of them come into the world blind, and continue for some time before they receive the sense of seeing. How many changes are exhibited in the dog from birth till he becomes a perfect animal, till all his members are completely formed, and all his instincts are unfolded and improved by experience and education! The deerkind acquire not their magnificent and beautiful horns before the age of puberty; and even these are annually cast off and renewed. Similar changes take place in quadrupeds of every denomination.

Many birds, like quadrupeds, are blind for some time after they are hatched. In this condition, how different are their form and appearances from those of the perfect animals! At first, they are covered with a kind of down instead of feathers. Even after the feathers shoot, they are often of a colour

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