Haruesty, spinal Neii'cs of the Frog. 95 



third order. They have been demonstrated both after treat- 

 ment with osmic acid followed by maceration in a mixture of 

 glycerine and hydrochloric acid and by means of methylene blue. 

 In preparations pressed out under the cover glass rather than 

 teased, numerous cases have been observed in which the fiber 

 splits at the angle formed by the division of the nerve branch, 

 one branch of the divided fiber passing into each branch of the 

 divided nerve. 



The splitting of the fiber occurs, as would be expected, at 

 a node, and there is no diminution in the diameter of the 

 fibers which result from the splitting. Each of the fibers — 

 sometimes three in number — which result from the division 

 possesses a diameter about the same as that of the fiber which 

 divided to form them. 



It has already been noted in this paper (Table XI) that 

 there is a marked correlation between the actual number of 

 fibers in the dorsal branches of the spinal nerves and the amount 

 of the excess of fibers in the sum of the trunk and these dor- 

 sal branches above the sum of the fibers contained in the two 

 roots. In those nerves in which the excess is greater the num- 

 ber of fibers in the dorsal branches is both absolutely and pro- 

 portionately greater. The dorsal branches going to the dorsal 

 muscles and to the skin of the back may be looked upon as 

 branches of the spinal nerve just as well as the branches to the 

 muscles and skin of the leg are branches of the sciatic nerve, 

 and if some of the fibers in the branches of the sciatic are the 

 result of splitting then some of the fibers in the dorsal branches 

 of the spinal nerves may be the result of splitting and hence a 

 splitting of fibers in and on the distal side of the spinal gang- 

 lion may be one cause for the excess of fibers present on the 

 distal side of the spinal ganglion. 



In order to determine the truth of this assumption an exam- 

 ination of the fibers in the region of the spinal ganglion is now 

 in progress. At the present stage of this investigation a state- 

 ment may be here inserted to the effect that divided fibers have 

 been frequently noted in the dorsal branches well outside the 

 limits of the ganglion but so far, such cases have been much 



