124 RESPIRATORY EXCHANGE OF ANIMALS AND MAN 



Hibernation in Mammals. 



A small number of mammals (but not a single bird) show the 

 peculiarity that their temperature regulation at times ceases to func- 

 tion, with the result that the temperature of the body falls and the 

 animals get into a state of torpor. By stimulations of different kinds 

 a process of awakening can be induced which is characterized by a rapid 

 increase in body temperature and a resumption of the normal functions. 

 The hibernation problem has been studied repeatedly from the point 

 of view of the metabolic processes, but the results are far from satis- 

 factory which is perhaps only natural when the very great difficulties 

 inherent in the investigation are duly considered. 



The transition from the ordinary to the hibernating state has been 

 studied by Pembrey and White [1896, I, 2] on dormice and bats. 

 They found that the muscular activity is the chief factor determining 

 the temperature and metabolism of these animals, while the physical 

 regulation of the loss of heat from the body is unimportant. An active 

 animal will maintain and even increase its temperature (by increased 

 activity) when the surrounding temperature falls, but as soon as it be- 

 comes quiet the metabolism and the body temperature drop very 

 rapidly as seen from the examples quoted. 



TABLE XXXI. 



In an experiment on the metabolism made by means of the 

 Haldane apparatus the sleepy dormouse was in the ventilated chamber 

 in a water-bath of 25 for 30 minutes before the first period of deter- 

 mination and thereupon consecutive periods of 15 minutes each 

 were taken. 



