The philosophy of natural history / by William Smellie ; with an introduction and various additions and alterations intended to adapt it to the present state of knowledge by John Ware.

  • Smellie, William, 1740-1795.
Date:
1824
Catalogue details

Licence: Public Domain Mark

Credit: The philosophy of natural history / by William Smellie ; with an introduction and various additions and alterations intended to adapt it to the present state of knowledge by John Ware. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    destitute of wings, must pass tluou^ii several changes before the animals arrive at the perfection of their natures. The appearance, iho structure, and the organs of a caterpillar, of a chrysalis, and of a fly, are so different, that, to a p Unacquainted with their transformations, an identical animal would be considered as three distinct species. Without the aid of experience, who could believe that a butterfly, adorn** ed with four beautiful wings, furnished with a long spiral proboscis or tongue, instead of a mouth, and with six legs, should have proceeded from a disgusting, hairy cat- erpillar, provided with jaws and teeth, and fourteen feet? Without experience, who could imagine that a long, white, smooth, soft worm, hid under the earth, should be transform- ed into a black, crustaceous beetle, having wings covered with horny elytra, or cases ? Upon this branch of the subject, we shall, first, give an ex- ample of two of the most common transformations of insects; and, secondly, describe some of the more uncommon kinds. Beside their final metamorphosis into Hies, caterpillars under- go several intermediate changes. All caterpillars cast or change their skins oftener or more seldom, according to the species. Malpighius informs us, that the silkworm, previous to its chrysalis state, casts its skin four times. The first skin is cast on the 10th, 11th, or 12th day, according to the nature of the season ; the second in five or six days after; the third in five or six days more ; and the fourth and last in six or seven days alter the third. This changing of skin is riot only common to all caterpillars, but to every insect whatever. Not one of them arrives at perfection without casting its skin at least once or twice. The skin, after it is cast, preserves so entirely the figure of the caterpillar in its head, teeth, legs, colour, hair, Sec. that it is often mistaken for the animal itself. A day or two before this change happens, caterpillars take no food; they lose their former activity, attach themselves to a particular place, and bend their bodies in various directions, till at last they escape from the old skin, and leave it behind them. When about to pass into the chrysalis state, which is a state of imbecility, caterpillars select the most proper places and modes of concealing themselves from their enemies. Some, as the silkworm, and many others, spin silken webs round their bodies, which completely disguise the animal form. Others leave the plants upon which they formerly fed, and hide themselves in little cells which they make in the