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THE AMERICAN NATURALIST 



[Vol. L 



such profound physiological changes, in some respects 

 almost as striking as the latent vitality of the seeds of 

 plants and the spores of lower organisms, has aroused the 

 attention of a great many observers. In fact, the liter- 

 ature on hibernation dates back to the time of Aristotle 

 (38^-322 b.c), though real experimental work for the 

 purpose of understanding the nature and cause of this 

 torpid state, commenced with Conrad Gessner 1 (1551). 

 From that date to the present there has accumulated a 

 vast amount of data, the bibliography of which is now 

 very accessible, due to the extensive works of Eaphael 

 Dubois, 2 published in 1896, and of Osvaldo Polimanti, 3 

 published in 1912. 



As the exciting cause of so-called winter-sleep, cold has 

 naturally received by far the greatest share of attention. 

 A rapid survey of the subject shows that much difference 

 of opinion has existed in regard to the manner in which 

 cold acts and what other factors are involved. Buffon 4 

 (1749) and Lacepede 5 (1829) thought that the blood 

 simply becomes cold when the small amount of heat pro- 

 duced by hibernating animals is not aided by the sur- 

 rounding temperature. The cold blood then produces the 

 changes characteristic of torpidity. Spallanzani 6 (1787), 

 however, considered that he had experimentally demon- 

 strated that the cold acts on the solid tissues of the body 

 and not on the blood. According to him the lethargy is 

 due either to the stiffening of the muscles or to the deple- 

 tion of the cerebral blood vessels. On the other hand, 

 Alibert 7 maintained that the cold diverts the blood from 

 the periphery to the vessels of the brain and the resulting 

 congestion causes torpor. But Serbelloni 8 (1866) claims 

 to have found the vessels of the brain nearly empty in the 

 case of three marmots in full hibernation. Hunter 9 (1775) 

 and Serbelloni explained that the cold causes the animal 

 to lose its appetite and in the absence of hunger, which is 

 a stimulus, the animal retires. 



A long list of authors, Daubenton 10 (1760), Geoffroy, 11 

 Cleghorn, 12 Allemand, 13 Carlisle 14 (1805), Barkow 15 



