Bell speaks of hibernation as ‘amongst the most remarkable and interesting phenomena which occur in the history of animals.’ It is not a state of suffering, like that of a warm-blooded creature that is frozen to death; but with one common impulse, reptiles all retire, and remain in an almost lifeless repose, with every function so nearly suspended, that no external signs of existence are visible. For them it is a sort of rest, and we may cease to wonder at their longevity since they live only half their lives. It is, indeed, a convenient mode of getting through life, reminding us of a theory or proposal ventilated not long since, by which convicts were to be economically provided for by submitting them to a certain freezing process, and disposing them neatly on rows of shelves until the expiration of their term of punishment; all to be done then was to dust them thoroughly—perhaps scrub them a little—and restore them to the world and life again. And they were promised to be none the worse, not even to have lost their memory or to have acquired the rheumatism. Unfortunately the wonderful process has never been made clear to anxious inquirers, or some others of us, who are _not_ convicts, might gladly resort to this method of rest occasionally, and of freezing out the worries of existence. On the principle of political economy, this would be all very well, and in the great routine of nature there is beneficence in the hibernation of creatures, whether reptiles or other animals, that are sent to sleep at the very time when food fails them. The smaller members of the class have no longer insects and molluscs; the larger ones feed chiefly on rodents and birds which have also retired or migrated, or on their lesser kinsfolk, that no longer abound where most wanted by them. Therefore, this going to sleep every winter, and doing without food when there is no food to be had, is most convenient for a considerable section of animated nature. There is something strangely analogous in the almost total suspension of vital forces in reptiles to that which vegetation undergoes. Circulation stops, the juices become stagnant, whether in a tree or in a snake, and it is sometimes difficult to decide in either case whether life is extinct or not. But with returning warmth comes renewed vitality; the fluids, whether of the animal or the vegetable organism, are thawed by the revivifying solar rays, which set them circulating and start the pulsation; and the animal machinery, like a watch wound up, is set in working order again. It is owing to this lack of warmth in themselves that snakes can live only in hot countries, or in cooler latitudes, during the warmer weather, and not at all in the frigid zones. In speaking of them, Dumeril says Linnæus was right in calling them cold animals in hot countries. ‘Aussi la plupart des Ophidiens habitent-ils les climats chauds, et c’est en parlant d’eux que Linné a pu dire avec raison: “Frigida æstuantium animalia.”’[47]