Page:Popular Science Monthly Volume 77.djvu/370

364 hibernating animal does not keep much above it, until a point is reached when the animal wakens. Then its temperature rushes up many degrees in a few minutes and at the same time the excretion of carbon dioxide becomes enormously increased.

Hansmann describes the influence of temperature on the incubation period and the formation of antitoxine. He found much greater resistance to infection and lengthened incubation time and no production of the various antibodies during hibernation. Blanchard and Blatin made the observation that in the hibernating condition the marmot was immune to parasitic maladies.

It may be stated and accepted that when hibernation has been fully investigated, all degrees of cessation of functional activity of the various organs and tissues will be found represented, from the normal sleep of man and other animals to the lowest degree of activity manifested in life. Though some observers claim that in true hibernation there is complete cessation of function in some organs, as, for example, the lungs and movements of respiration, this is extremely doubtful. The awakening of an animal from its winter sleep is never sudden, but slow and gradual, often lasting for hours. This gradation from a passive to an active condition is no doubt protective to the vital machinery, as it has been noticed that when bats have been awakened suddenly they have quickly died.

We have spoken of hibernation in man, and by some authorities, sleep in man is closely allied to a state of hibernation. Natural daily sleep is favored by moderate exhaustion, the cravings of hunger being satisfied, and the absence of all peripheral stimuli. Sleep is a rhythmic diminution of the activities of all the tissues, but especially of the nervous system, which has control of all the others. As we have mentioned before, Marshall Hall and others have shown that the gaseous interchange in a hibernating animal is greatly lessened and so too it is in sleep. It has also been shown by experiments that hibernation, like daily sleep, is not a series of fixed and rigid phenomena, but is varied in depth and in season and its main use is that of protecting and conserving life.

All forms of profound winter and summer sleep are protective, both of the individual and of the species. If it were not for this act of hibernation, many of the mammalia, amphibia, as well as some other groups of animals, would be utterly destroyed from the face of the earth.