Abstract
IN THE ANIMAL KINGDOM adverse environmental conditions are met by many interesting adaptations: certain protoz0a develop cysts; many insects pii′ pate; the Australian lungfish burrows into the mud and secretes a gelatinous capsule which enables it to survive the dry season; certain mammals in the temperate sone react by an interesting and complex state known as hiberna′ tion. These mammals depend upon insects and grasses for their chief source of food. Many of them live in frozen subterranean burrows during the long winter months. Characteristically they are able to tolerate cold (Horvath's Test),2 they have an unstable temperature regulating mechanism, they show a striking increase in their body weight during the summer months and are sexually inactive during the winter. This phenomenon of hibernation is a seasonal defense reaction in which homiothermic forms become poikilo′ thermic, thus enabling them to survive long periods of low temperature and diminished food supply at the expense of their extensive...
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