THEORIES OF HIBERXA T10X 



619 



of migration in birds, he thinks, may have developed in 

 remote ages, the prime cause being want of food, and not 

 cold. 



Dubois 73 (1895) has developed a carbonic auto-narcosis 

 theory according to which hibernation is due to the accu- 

 mulation of C0 2 in the blood and tissues of the animal. 

 This excess of C0 2 is supposed to cause a form of nar- 

 cosis as seen in the torpid condition of the hibernating 

 animal. When the C0 2 reaches a certain concentration 

 the respiratory center is excited, respiration accelerated, 

 and the muscles become hyper-irritable. These culminat- 

 ing results are responsible for the awakening from dor- 

 mancy. The author claims that he can induce typical 

 hibernating sleep by causing the active marmot to breathe 

 a mixture of air (42 per cent), C0 2 (45 per cent) and 

 oxygen (12 per cent). Torpid marmots remain dormant 

 if supplied with this mixture. By increasing the propor- 

 tion of C0 2 respiration is accelerated, and if the supplying 

 of C0 2 is continued the hibernating marmot wakes up. 

 The C0 2 is supposed to act principally on a nervous 

 center for sleep situated in the mid-brain, since marmots 

 deprived of cerebral hemispheres are able to sleep and 

 wake up ; but with only the medulla intact they are un- 

 able to awake. Further, Dubois 74 (1894) found that C0 2 

 actually accumulates in the blood during hibernation in 

 the marmot and decreases again when the animal wakes 

 up. Such an increase in the C0 2 content of the blood 

 during hibernation has just been observed in this labora- 

 tory in case of the woodehuck (M«nnota monax).' 



Upon sufficiently good authority 70 to receive the serious 

 consideration of such an author as Max Verworn, « cer- 

 tain ascetics of India, known as fakirs, arc able to volun- 

 tarily go into a condition of almost suspended animation 

 not unlike hibernation in some respects. While in this 

 condition it appears that these fakirs may be buried three 

 or four feet in the ground for days, or may be inclosed for 

 six weeks without food and with but little air in a tight 

 box which in turn is sealed up in some dark inner room. 



