I20 Journal of Comparative Neurology, 



would suggest a constitution of the cervical ganglion which was 

 different from that of the other two, since these two have nearly 

 twice the number of the large cells in proportion to the num- 

 ber of dorsal root fibers. It is possible that this difference is 

 to be explained by the presence of Dogiel's cells ('97) of 

 second type in the ganglia of the thoracic and the lumbar re- 

 gions, but Dogiel's statement would hardly support this as a 

 complete explanation, because he distinctly says that the cells 

 in the second type are comparatively few in number, whereas 

 the relation here given would demand a rather large number of 

 the cells. 



The excess in the number of the cells over that of the 

 fibers has been reported by several investigators : Hodge, 1888, 

 counted in the frog the number of fibers in the posterior 

 roots and the number of cells in the corresponding spinal gang- 

 lia, and found that one afferent fiber of the frog corresponds in 

 these cases to from 2.45 to 3.26 cells. Buhler, 1896, found 

 in the dorsal root of the ninth spinal nerve of the frog (Rana 

 esculenta) 680 fibers and in the spinal ganglia about 3500 cells, 

 giving a ratio of i to 5 ; Gaule and Lewin 1896, found 3173 

 posterior root fibers in the 32nd. spinal nerve of the rabbit and 

 20361 in the corresponding spinal ganglia; a ratio of 1:6.4. 

 We see that the excess in the number of spinal ganglion cells 

 has already been observed, but observations here given enlarge 

 our information by showing the excess found in different nerves 

 and at several ages, and, finally, that the ratio diminishes as the 

 animal grows larger. 



• From the present observations, it is probable that the im- 

 mature fibers are the processes of some of the large cells, as it 

 will be seen from Table VI that the total number of the large 

 cells exceeds the total number of the fibers. From this fact it 

 js improbable that the immature or smaller fibers in the dorsal 

 root are the processes of the small cells. The excess of the 

 number of the fibers (See Table IV) may be partly explained 

 by the presence of a greater or less number of the apolar cells, 

 in the sense of the early investigators, in the spinal ganglia for 

 the cells of the second type of Dogiel ('96, '97) (according to 



