336 Journal of Comparative Neurology. 



VI. The Excess of Fibers on the Peripheral Side of the 

 Spinal Ganglion, 



This question was touched upon in the previous paper 

 ('99). It was shown there (Tables XI and XII, p. 87) that 

 among the various spinal nerves of a given specimen, those 

 nerves which have the greatest distal excess have also both 

 absolutely and proportionally the greatest number of fibers in 

 their dorsal branches. In other words, the number of fibers 

 constituting the distal excess and the absolute and proportional 

 number of fibers of the dorsal branches tend to coincide. It 

 was seen also that, of all the spinal nerves, the 6th. possesses 

 the greatest proportional and absolute number of fibers in its 

 dorsal branches and therefore shows a greater percentage value 

 for the distal excess than any of the other nerves. For the 

 specimens previously used, it was seen that the distal excess for 

 the 6th, nerve might be as much as 40 % . In this series, it 

 will be seen that the 6th. nerve may have a distal excess as 

 great as 61%. 



An excess of fibers on the peripheral side of the spinal 

 ganglion has been found by other observers. Birge ('82), made 

 some counts of the fibers in the two roots and nerve trunk of 

 the spinal nerves of the frog. He did not include the dorsal 

 branches at all, and nevertheless found two nerves in which the 

 fibers in the trunk alone exceeded the sum oi the two roots. 

 He was at a loss to explain this excess. 



Gaule and Lewin ('96) counted the fibers on the central 

 and peripheral side of the spinal ganglion of three of the sacral 

 nerves of the rabbit. They included the dorsal branches and 

 found distal excesses of 11%, 15%, and 19% respectively. 



Buhler ('98), in a very interesting paper dealing with the 

 structure of the spinal ganglion cells, in order to compare the 

 number of fibers with the number of cells in the ganglion, 

 counted the fibers present on both sides of the ganglion. The 

 one case in which he reports having done this was that of a 9th. 

 spinal nerve of the frog and there he found a distal excess of 

 25.5%. Buhler does mention having included the dorsal 



