;>!M A. T. UASMUSSEN AND J. 



I'RKSKNT INVESTKIATION 



In view of the conflicting reports as just reviewed and the 

 more recent observations by Crile on changes in the brain cells 

 under various emotional and other conditions, much less strik- 

 ing than the phenomenon of hibernation, the work we have done 

 on the woodchuck in this regard, seems worthy of a brief note. 

 Woodchucks, or ground hogs, which represent the American 

 marmots, are some of the best examples of hibernating mammals 

 in this country. All s]:»ecies remain dormant for four to six 

 months each year, and hence constitute good material for a 

 study of hibernation. This work was commenced early in 

 January 1913 by J. A. Myers, who fixed and imbedded the 

 central nervous system of six woodchucks, four of which were 

 killed at various intervals while hibernating (January 18, Febru- 

 ary 6, March 15 and April). One was killed shortly after waking 

 up (March 15) and another, during the following summer. 



In addition to studying the above series by means of the 

 Nissl stain, the other co-author prepared another series consist- 

 ing of the brain and spinal cord of fifteen woodchucks killed 

 during the autumn, winter and spring of 1913-1914. This series 

 includes one animal killed about a month before hibernation 

 (October 25), one just before hibernation (November 22), five 

 during hibernation (February and March) — one of these was 

 partly awake when killed on February 16, but was sluggish 

 and had a rectal temperature of 19°C. — one within two days 

 after waking up (March 16) and seven others which had been 

 awake from three days to more than a month. Three of this 

 last group had been fed for one, two and three weeks respectively. 

 These animals were kept in the artificial burrows which were 

 designed by Professor Simpson of this laboratory and which 

 have already been described elsewhere.^ The rectal temper- 

 ature of the dormant animals varied from 8°C. to 12°C., whereas, 

 the temperature of the active animals ranged from 32°C. to 

 38°C. 



' Rasmussen, A. T., Amer, Jour. Physiol.. 1915, vol. 39, p. 20. 



