R ANSON, Ahcrati()}is in Spinal Gdiiglioii Cells. 135 



ditions of tlic experiment the secondary or consecutive alterations 

 make tlieir appearance. These are of three kinds: (1) repair, which 

 occurs in a considerable proportion of the cells and consists of a 

 restoration of the Nissl bodies and a return of the nucleus to the 

 center, of the cell ; ( 2 ) atrophy, which occurs in nearly all the cells 

 that undergo repair and results in a very considerable shrinkage 

 of the cell body and its nucleus; (3) progressive degeneration leading 

 to the complete destruction of all those cells Avhich fail to undergo 

 repair. 



The phase of reaction has been most carefully studied and all 

 the essential features of the intra-cellular changes have been described 

 many times. Accordingly, we shall have chiefly to consider at this 

 time the relative susceptibility of the different types of cells, and 

 pay but little attention to the finer details of chromatolysis. The 

 measurements of Lugaro and Fleming supply us with satisfactory 

 data as to the atrophy taking place in the cells ; but the observations 

 on the phases of repair and degeneration are of the meagerest sort. 

 It is with regard to these two late phases that the present investiga- 

 tion has given the most suggestive results. 



The Phase of Reaction. Due in part, perhaps, to the peculiarities 

 of the type of animal but more to the immaturity of the individuals 

 used for the experiments, chromatolysis occurs very early in the 

 second cervical ganglion of the young white rat. Five days after 

 an operation performed on a ]*at 12 days old chromatolysis is already 

 far advanced and is, in fact, at its highest point. Even in the largest 

 cells there remains but a narrow peripheral ring of undissolved 

 Nissl-granules. The tumefaction of the cells and the peripheral 

 dislocation of the nuclei are as pronounced on the fifth day as at 

 any subsequent time (Fig. ?>). 



All authors, Lugaro, Fleming, Cox, Cassirer, Koster, and War- 

 rington and Griffith, agree that the vast majority of the cells in the 

 spinal ganglion react to a lesion of the peripheral nerve. There is 

 some difference of opinion as to the exact proportion ; while Koster 

 asserts that all the cells react, the remaining authors make an excep- 

 tion of the very smallest cells in the ganglion, and Cox, Warrington 

 and Griffith also find a small percentage of the large cells that do 



