630 



AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



Table showing the Decrease in the Volume of the Nucleus of Stimulated Spinal 

 Ganglion-cells of Cats. Stimulation for fifteen seconds alternating with 

 rest for forty-five seconds (Hodge). 



Stimulation continued 



for- 

 1 hour 

 2.5 hours 

 5 " 

 10 " 



Shrinkage in the volume of the nuclei 

 of the stimulated cells. 

 22 per cent. 

 21 " 

 24 " " 

 44 



This table further shows that the shrinkage is greater, the greater the time 

 during which the stimulus was applied. There is thus established not only 

 the fact of a change in the cell, but also a connection between the amount of 

 this change and the length of time during which the stimulus was allowed to 

 act. The results when expressed by a curve yield the following : 



Per 



cent. 

 100 



90 

 80 

 70 

 60 



50 

 Hours 



\ 





1 2i 5 10 Hi 17 



FIG. 158. The broken line indicates the volume of the nuclei of the spinal ganglion-cells of a cat 

 after stimulation for the times indicated. The solid line indicates the volume of the nuclei, first after 

 severe stimulation for five hours, and then in other cats, also stimulated for five hours, but subsequently 

 allowed to rest for different periods of time. The period of rest is found by subtracting five hours from 

 the time at which the record is made. After twenty-four hours of rest the nucleus is seen to have 

 regained its normal volume (Hodge). 



Table to show Influence of Rest. 



Right brachial plexus of each Cat stimulated in the same manner for. five hours. Cat allowed 

 to rest for a variable time after the stimulation had been stopped. 



Whether these changes could be considered similar to the normal physi- 



