708, 



PHYSIOLOGY. 



That the absence of sensory impulse has an important action in 

 promoting sleep is shown by the case of a boy who had only one eye 

 and one ear to keep him in touch with the external world. All other 

 avenues of sensory impulses were abolished. If now, these avenues of 

 impulse were abolished by bandaging the ear and eye, the boy would 

 fall asleep. If a dog is kept awake five days he will die. This wake- 



Fig. 286. Pyramidal Cells of the Marmot in Two Different Conditions. 

 (After QUERTON.) 



On the left, pyramidal cell of the marmot asleep; on the right, that 

 of the marmot awake. 



fulness is attended with a lowering of temperature (8 C.), dimin- 

 ished reflex activity, and changes in the brain. In man, loss of sleep 

 causes a slight increase in weight. The excretion of nitrogen, and 

 especially that of phosphoric acid, is increased by the want of sleep ; 

 acuteness of vision is also increased. But when the man is permitted 

 to make up for this loss of sleep, there is a complete disappearance 

 of the just-mentioned conditions and a normal state ensues. 



