308 



MESSRS. F. GOTCH AND V. HORSLEY 



2. Alterations in Resting Difference. 



(a.) Physical Changes. The alterations due to drying probably have the same 

 influence as that already alluded to in the case of the sciatic nerve. The amount of 

 the difference noticed immediately after section generally increases slowly and steadily, 

 and, at least partially, from this cause. There is, however, a noticeable check in the 

 rise after the first five minutes, after which the difference then only in some cases 

 begins to fall. Hence either the rise is accentuated at first by some other agency, or 

 it is counterbalanced by the depressant effects due to loss of vitality. 



(6.) Physiological Changes. The amount of the difference in the root diminishes 

 with greater rapidity than in the case of the nerve trunk, in consequence of systemic 

 death. A similar fall occurs if the root is severed from its central connection. This 

 is illustrated by the following series of experimental observations made before and 

 after the death of the animal. 



LEFT 7th Lumbar Posterior Boot.* (Cat, 362.) 

 Root Divided near Ganglion and Central End Connected with Electrodes. 



ROOT cut off from Cord. 



In another animal after systemic death had caused a decline in the amount of 

 difference, severance of the root caused no further appreciable decline. 



* See Plate 35. 



