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remained three years and a half, and readily revived when again exposed to the influence of a warm atmosphere.

Why do reptiles respire very slowly during their torpidity

Because the circulation of the blood is carried on independent of the action of the lungs. Even in a tortoise, kept awake during the winter by a genial temperature, the frequency of respiration was observed to be diminished.

The circulation of the blood is diminished, in proportion to the degrees of cold. Spallanzani counted from 11 to 12 pulsations in a minute in the heart of a snake, at the temperature of 48°, whose pulse in general, in warm weather, gives about 30 beats in the same period. Dr. Reeves observed the number of pulsations in toads and frogs, to be 30 in a minute, whilst they were left to themselves in the atmosphere, of which the temperature was 53°; when placed in a medium, cooled to 40°, the number of pulsations was reduced to 12 within the same period; and when exposed to a freezing mixture at 26, the action of the heart ceased altogether. The powers of digestion are likewise equally feeble.

Why has the immediate cause of torpidity in reptiles, been ascertained with more precision than in animals with warm blood?

Because this condition with them, does not depend on the state of the heart, the lungs or the brain; for these different organs have been removed by Spallanzani, and still the animal became torpid, and recovered according to circumstances. Even after the blood had been withdrawn from frogs and salamanders, they exhibited the same symptoms of torpidity, as if the body had been entire, and all the organs capable of action. Why are there but few reptiles in the cold countries of the globe?

Because they are so easily acted upon by a cold atmosphere; while in those countries enjoying a high temperature, they are formed of vast size, of many different kinds, and in great numbers.

REPTILES.

TORTOISE TRIBE.

Why are tortoises enabled to bear such immense weights?

Because most of them are covered with a firm long shell, the upper part of which is connected with the spine and ribs, and is covered by the broad horny plates, which in many species are so firm, and of such beautiful colours as to be employed for various purposes of art. There are usually thirteen such plates in the middle, and twenty-four round the edges. The under-shell, covering the belly, is somewhat smaller than the upper, with openings for the head, the tail, and the feet.

The

In a Singapore newspaper we read, that the tortoise, when caught by the Eastern islanders, is suspended over a fire, kindled immediately after its capture, until the effect of the heat loosens the shell, so that it can be removed with the greatest ease. animal, now stripped and defenceless, is set at liberty. If caught in the ensuing season, or at any subsequent period, it is asserted that the unhappy animal is subjected to a second ordeal of fire, rewarding its captors this time, however, with a very thin shell.

We do not quote this fact for its refinement of cruelty, but to prove the tenacity of life in the tortoise, which must be accounted a very singular fact in natural history.

Blumenbach observes, that the peculiar and distinct form of this consequently isolated genus, forms a very strong proof of the non-existence of the supposed gradation of objects in nature.

Why have animals of the tortoise tribe, usually jaws provided with a horny covering, like the bills of birds? Because they are destitute of teeth.

Why do these animals deposit their eggs in the sand? Because they may there be hatched by the heat of the sun. A single nest has been known to furnish 500

eggs.

Why are the eggs of the land-turtle more likely to be discovered than those of the water-turtle ?

Because the former leaves its eggs, one by one, as it hobbles over the ground, neither covering nor taking any care of them whatever, nor paying any regard to the offspring. The water turtle, on the contrary, covers its eggs so accurately as to leave no signs perceptible of its nest; and, however strange it may seem, she so arranges it as to make her tract appear unbroken over the sands, and, after laying her eggs, she proceeds on again in the same direction to complete the deception. Why is the flesh of the green turtle so well-tasted, and free from oil?

Because it feeds solely on sea-weeds. It is named from the pale olive-green colour of the shell, and the still more remarkably green colour of its fat. This species sometimes weighs 800 weight.

Why is the geometrical tortoise so called?

Because its high-arched shell is very regularly marked with black and yellow.

FROGS AND TOADS.

Why have certain frogs been fabulously said to change into fishes?

Because their larva is almost a span long, and then' much larger than the perfectly formed animal. The animal also retains its tail for some time after the four legs have acquired their perfect form and size.

Why is the tree frog so called?

Because it climbs trees in search of insects; for

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THE NEW YORK PUBLIC LIBRARY

ASTOR, LENOX AND
TILDEN FOUNDATIONS.

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