Volume XII 1902. Number 2 



THE 



Journal of Comparative Neurology. 



NUMBER AND SIZE OF THE SPINAL GANGLION 



CELLS AND DORSAL ROOT FIBERS IN THE 



WHITE RAT AT DIFFERENT AGES. 



By Shinkishi Hatai. 



{Front the Neurological Laboratory of the University of Chicago.') 



I. Introduction. 

 II. Material used and technique employed for the present investigation. 



III. On the spinal ganglion cells. 



A. Total number of the spinal ganglion cells at different ages. 



B. Ratios of Inrge to small cells. 



IV. The dorsal roots. 



A. Total number of the dorsal root fibers at different ages. 



B. Ratios between the completely formed and immature fibers. 



V. The relations of the number of spinal ganglion cells to the number 

 of dorsal root fibers. 

 A. Ratios between the large cells and total number of fibers in the 

 dorsal roots. 

 VI. The size of the cell-body, the nucleus, and the fibers at different ages. 

 VII. Sutiiniary. 



I. Introduction. 



The present investigation was undertaken for the following 

 reasons : 



(i). In my previous paper (1901, I) on the small spinal 

 ganglion cells in the white rat, these cells were considered to 

 be immature and growing. In that paper, the following state- 

 ment was m,ide, "From these several observations the writer 

 concludes that the small cells of the spinal ganglion are in a 

 growing state or in a more or less permanently immature con- 

 dition. The growing fibers (1899) which are found in an adult 

 frog might, therefore, very well be formed by the axones of 

 these latent cell-bodies." If this interpretation was correct, 

 then the number of the small cells should decrease with age, 

 and at the same time, the number of the large cells siiould 

 increase. ' 



