No. 598] 



TIIF.OJUKS OF JIlDKliX A TIOM 



611 



(1846) and others, have emphasized also the necessity of 

 confined air or diminished respiration, ('leghorn and 

 Allemand maintaining that this is tlx' principal cause. 

 Reeve 16 (1809) said that such a condition favors winter- 

 sleep, while Bert 17 (1868) first concluded that lack of 

 oxygen and then later 18 (1873) that the accumulation of 

 C0 2 in the surrounding air might be the cause of dor- 

 mancy. Mangili 19 (1807), however, denied that vitiated 

 air has anything to do with this torpid state and Dubois- 

 (1896) says that confined air is not necessary, for animals 

 hibernate perfectly in well-ventilated plaees. 



Marshall Hall 21 (1832) believed that the cold caused 

 ordinary sleep, which diminishes respiration, and less 

 heat is produced. Lessened respiration causes the blood 

 to lose its arterial character and hence its power to stim- 

 ulate the heart. The heart, however, changes its irrita 

 bility so that it does not stop. This change in the irri- 

 tability of the heart, then, is the important factor in 

 liilicrnation. To him \vinter->leep is -oinet liing entirely 

 different from the torpor produced by cold. To Kdwards-- 

 (1824) and Legallois 23 (1824) sleep and cold are so bound 

 up with heat production that a failure to keep up the body 

 temperature causes torpidity to ensue. 



Throughout the literature of the last one hundred years 

 there is a strong tendency to consider hibernation as dif- 

 fering from ordinary daily sleep only in degree. Ed- 

 wards 22 (1824), Duge 24 (1838), Hall 21 (1832), Blandet 25 

 (1864), Patrizi 26 (1894), Dubois 27 (1896, 1910), Brunelli 28 

 (1902), Claparede 29 (1905), Allen Cleghorn 30 (1910) and 

 Salmon 31 (1910) make definite statements regarding the 

 striking similarity between ordinary daily sleep and 

 hibernation. Gemelli 32 (1906) used the facts obtained by 

 him from hibernating marmots, in disproving Salmon's 

 theory of sleep. Indeed, it has been the hope of many of 

 the students of hibernation to be able to throw some light 

 on the process of diurnal sleep in man and other animals, 

 by a study of what they have considered to be merely an 

 extreme example of this physiological condition. The 



