THEOBIES OF HIBEENATION 



ANDREW T. RASMUSSEN 

 Cornell University 



An examination of the literature on almost any par- 

 ticular natural phenomenon often reveals the fact that 

 many different theories have been advanced to explain it. 

 Some of these explanations may be mere opinions based 

 upon no or but few scientific facts. One is also frequently 

 struck with the immense literature that has been produced 

 and the great gap that still intervenes between the ac- 

 cumulated facts and a clear understanding of the proc- 

 esses which they aim to elucidate, even after more than 

 a hundred years of experimental work, which has usually 

 been preceded by a much longer period of speculation by 

 the great thinkers of the past. So that while we con- 

 gratulate the last few generations upon the rapid growth 

 that has been made in scientific knowledge, there yet re- 

 main phenomena that are almost as unintelligible to-day 

 as they were a hundred years ago— the most earnest and 

 often tedious experimentation and observations of sev- 

 eral generations having shed but little light on the fac- 

 tors and mechanism involved. 



The extremely interesting fact of hibernation (called 

 "Winterschlaf" by the Germans, "sommeil hivernal" by 

 the French and "letargo" by the Italians) illustrates well 

 the above point. As is well known, during this dormant 

 state the vital processes are greatly reduced. The changes 

 that occur are especially marked in certain mammals, 

 since they apparently undergo a rather sudden transfor- 

 mation from the warm-blooded (homoiothermal) type to 

 the cold-blooded (poikilothermal) type. In the latter 

 state such mammals are able to endure cold, deprivation 

 of food, confined air, effects of many drugs, and other 

 conditions that would be fatal at other times. Naturally 

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