122 THE PHYSIOLOGY OF MUSCLE AND NERVE. 



the nerve fibers in the central stumps may also show atrophy, 

 while others undergo a genuine degeneration, which, however, 

 comes on much later than in the peripheral stumps. It seems 

 evident that the behavior of the cells and fibers on the central side 

 of the section is not uniform; atrophy rather than degeneration is 

 the change that is prominent, and this atrophy in some neurons 

 occurs early, while in others it is apparent only after a long interval 

 of time. An explanation of this variation in the reaction of the 

 nerve cells and their disconnected central stumps cannot yet be 

 given. On the peripheral side of the section, as stated above, the de- 

 generative changes are complete and affect all of the fibers.* 



*Nissl, "Allgemeine Zeitschrift f. Psychiatric, " 48, 197, 1892. Also 

 Bethe, loc. tit., and Ranson, "Retrograde Degeneration in the Spinal Nerves," 

 The Journal of Comparative Neurology and Psychology, 1906, xvi., 265. 



