MITOCHONDRIA IN NERVE CELLS 39 



ered very labile, are doubtful (Rasmussen and Myers, '16). It 

 was hoped that the enormous reduction in nearly all, if not all, 

 vital processes of such animals during winter-sleep would add 

 one more link to the chain of evidence for or against some of the 

 theories concerning the connection between mitochondria and 

 functional activity. Since alterations in the nervous system are 

 important factors in all the more thoroughgoing hypotheses con- 

 cerning the cause of hibernation (Rasmussen, '16 a), the facts 

 discovered would be of interest also in connection with the mech- 

 anism involved in the production of dormancy. 



MATERIALS AND METHODS 



In this investigation there are involved fifteen adult wood- 

 chucks of the lot used in connection with a determination of 

 blood volume as already reported (Rasmussen and Rasmussen, 

 '17). The conditions under which the animals hibernated is 

 there described. Five animals (two females and three males) 

 were sacrificed between December 1st and December 3rd, just 

 before the onset of hibernation, while still active and under full 

 feed. Five others (two females and three males) were killed 

 while dormant during the last few weeks of hibernation (between 

 February 26th and March 18th). The remaining five (two fe- 

 males and three males) were bled between April 3rd and April 

 18th while active and after having been awake from four days to 

 three weeks, but without having available any food or water 

 either during or after winter-sleep. 



After the blood was washed out by gradual perfusion with 

 oxygenated Locke's fluid, warmed or cooled to the body tempera- 

 ture, according to the technique employed by Dreyer and Ray 

 ('11), the vessels were flushed out with physiological salt solution 

 and then Regaud's fixer (one part of commercial formalin neu- 

 tralized with magnesium carbonate and four parts of a 3 per 

 cent aq. sol. potassium bichromate) was allowed to perfuse the 

 entire animal for an hour. In order to see if the length of the 

 perfusion with Locke's solution had any noticeable effect on the 

 mitochondria, the last animal of each of the three groups was per- 

 fused only long enough to cause a return of a colorless fluid from 



