Don't miss the big stories. Like us on Facebook. Mammals and birds are endotherms, which means they generate their own body heat through relatively high metabolic rates. That high metabolism requires ...

I TRUST your correspondent of “X” will not object to my pointing out that the “hibernation” story which he retails in NATURE (vol. xvi., p. 43) has in common with dozens, not to say scores, of others, ...