As to the suspension of breathing in hibernators, the fact is proved sufficiently in the instances of the raccoon and the woodchuck. When they have laid themselves away for the winter sleep they roll themselves up comfortably and press their noses in such a position against their hinder parts that it would be an absolute impossibility for them to draw a breath. It is generally supposed that the bear rolls itself up in this way and does not breathe, but the holes melted in the snow beneath which the animal frequently stows itself, under a covering of leaves, prove that it does breathe while in its lethargy. The marmot family produces the soundest winter sleepers. When the marmot is in its peculiar state of hibernation the electric spark will not rouse it. The most noxious gases do not affect it in the slightest. If its temperature is raised above that at which the animal breathed in its natural state it will die almost immediately. Our own familiar wild animals, the bear, the raccoon, and the woodchuck--the so-called ground-hog--are classed as perfect hibernators, because they store no food for winter, but have acquired or provided themselves with a thick, fatty secretion between the skin and flesh, which, it is supposed, supplies them with sustenance. As a matter of fact, although dormant animals absorb fat, it does not enter into their digestive organs. Food introduced into the stomach of a hibernating animal, or reptile, by force or artificial means, will be found undigested at all stages of its lethargy, for it invariably goes into its peculiar state on an empty stomach. That is one of the mysteries of the phenomenon, not so great, however, as the fact that bears and woodchucks produce their young during their winter sleep. The male bear is frequently roused from his sleep and is found by the woodsman roaming about in mid-winter, but they have never known, they say, a female bear to be killed after the season for hibernation has set in. Squirrels are only partial hibernators, from the fact that they work all summer and fall storing great quantities of food to supply them when hunger wakes them up during the winter, some of them, no doubt, spending very little time in a lethargic sleep. The common land tortoise, no matter where it may be, and it is a voracious feeder, goes to sleep in November and does not wake up again till May, and that curious animal, the hedgehog, goes to sleep as soon as the weather gets cold and remains in unbroken slumber six months.