130 Journal of Comparative Neurology. 



stimulating the peripheral nerves. The pilo-motor nerves then 

 (like all visceral nerves) are connected at some point of their 

 course with nerve cells. * * *" The pilo-motor nerves 

 in the various rami of the superior cervical ganglion are typi- 

 cally all connected with the nerve cells in this ganglion. The 

 cervical rami of the ganglion stellatum, and the grey rami of 

 the first three thoracic nerves are connected with the nerve cells 

 in the ganglion stellatum. From the Vth thoracic to the Vlth 

 lumbar grey ramus inclusive, all the fibers of the grey ramus 

 are, as a rule, connected with the nerve cells in the corres- 

 ponding ganglion. 



It will not be necessary to describe in detail the experi- 

 ments which have led to the above conclusions, nor to do 

 more than to state that experiments with nicotin^show conclu- 

 sively that the grey rami consist largely of the neuraxes of the 

 sympathetic neurons of the respective ganglia. As to the fur- 

 ther course of the pilomotor nerves in the spinal nerves, Lang- 

 ley has shown : ' ' That so far as the skin is concerned, the dis- 

 tribution of all the sympathetic fibers which run to the spinal 

 nerve (grey rami) is the same as that of the sensory fibers of 

 the nerve, and that the distribution of the sympathetic fibers of 

 a spinal nerve can in the main be determined by dissecting the 

 nerve in its course." The white and gray rami differ therefore 

 in structure and function. The former consist of the small 

 medullated fibers, the neuraxes of neurons of the cerebro-spinal 

 axes, ending in baskets ; the latter of the neuraxes of the sym- 

 pathetic neurons in the ganglia, which become associated with 

 the spinal nerves. They form the terminal link of a neuron 

 chain of which the white rami form a portion of the second link. 

 In the grey rami are found a variable number of medullated 

 fibers, as has been shown by Gaskell, Langley and others. 

 Langley (91) states that their diameter varies from 2 m to 4 /< 

 and some fibers above this size 6 to 12 /< . Some of the 

 smallest are medullated sympathetic fibers ( KoUiker (32) 

 states jthat the pilo-motor fibers — " Haarbalgmuskeln-Nerven " 

 — of the cat are medullated sympathetic fibers); a few, 

 chiefly the medium sized and larger, come from the posterior 



