SYMPATHETIC GANGLIA 243 



As development advances, the distal portion of the oculomotor 

 nerve is carried cephalad. In the later stages of development, 

 therefore, this nerve curves anterio-ventrally toward the orbit. 

 The anlage of the ciliary ganglian still lies in immediate contact 

 with its lateral surface. 



During early development the ciliary ganglion is associated 

 solely with the oculomotor nerve. As development advances, 

 a slender ramus composed of fibers which emerge from the first 

 sympathetic ganglion and the anterior border of the Gasserian 

 ganglion grows cephalad and communicates with the ciliary gan- 

 glion. This fibrous ramus which constitutes the radix ciharis 

 longa, however, does not communicate with the ciliary ganglion 

 until the anlage of that ganglion has become well established. 

 The ciliary ganglion, therefore, obviously arises primarily from 

 cells which advance peripherally along the oculomotor nerve. 

 After this ganglion becomes connected with the Gasserian gan- 

 glion and the first sympathetic ganglion through the radix longa, 

 it, doubtless, receives cells which wander out from these latter 

 ganglia along this fibrous tract. Such cells, however, must 

 obviously be relatively few in number. 



THE AMPHIBIA 



Introductory 



Amphibian larvae have been favored objects of study in the "in- 

 vestigations of the development of the sympathetic nervous system, 

 yet little is known concerning either the development or the ana- 

 tomical relationships of the cranial portion of the sympathetic 

 system in this class of vertebrates. Amphibian larvae afford less 

 favorable material for the study of the development of the sym- 

 pathetic nervous system than do the embryos of many other verte- 

 brates. This division of the nervous system is relatively feebly 

 developed in both the Anura and the Urodela; consequently, the 

 sympathetic material present in their larvae is relatively meager. 

 This is even more apparent in the cranial than in the trunk region. 



