90 Journal of Comparative Neurology. 



Gaule and Lewin ('96) in a preliminary paper, give some 

 enumerations upon the nerves of the rabbit. At the time of 

 pubh'cation counts had been made of the fibers contained in the 

 two roots and in the trunk and dorsal branches of three of the 

 sacral nerves. These counts revealed respectively, 19/^, 11% 

 and i$fc more fibers in the trunk and branches combined, than 

 there were in the sums of the two roots. They are the first to 

 mention having included the dorsal branches in the enumeration. 



Biihje ('98), in a study of the spinal ganglia of the frog, 

 counted the fibers to be found on the central and distal sides 

 of the spinal ganglion. The original of this paper of Biihle 

 has unfortunately not yet been obtainable. According to a re- 

 view by Lenhossek ('97), Biihle obtained an excess of fibers on 

 the distal side of the ganglion which in one case amounted to 

 as much as 25.5 %. Even this, however, is less than the excess 

 here found for the Vth and Vlth nerves of the American frog 

 {R. virescens). 



To explain the excess of fibers on the distal side of the 

 spinal ganglion, Gaule ('96) suggested the only two possibilities: 

 (i) Fibers coming from the periphery may end in the ganglion 

 and thus not pass over into the dorsal root ; or, (2) fibers may 

 arise in the ganglion and pass toward the periphery without 

 there being a corresponding central process. 



Since the excess can be looked upon as well established, 

 the two possibilities suggested by Gaule may be presented in 

 some detail. 



I. Medullated fibers arising from the cells of the sympa- 

 thetic ganglia pass, by way of the ramus communicans and the 

 nerve trunk, to the spinal ganglion and end there. For the 

 existence of such fibers the evidence is as follows : 



Bidder and Volkmann ('42), noting the great number of 

 small medullated fibers present in the peripheral nerves of the 

 frog and especially in the sympathetic system, arrived at the 

 conclusion that these small medullated fibers originated in the 

 cells of the sympathetic ganglia, and they suggested the small 

 diameter as the characteristic by which the fibers of the sympa- 



