CoGHiLL, Cranial Nerves of Triton. 251 



occur on a connecting filament between the two nerves. Ordinarily, 

 however, there are no ganglion cells found on this nerve. In 

 all probability the cells which occur here belong to the few fibers 

 which in those instances connect the two divisions of the third 

 nerve, and do not contribute to the essential composition of the 

 nerve to the eye. 



The most natural interpretation of these nerve cells is that they 

 belong to the sympathetic system, and that they represent the 

 ciliary ganglion. But it is very improbable that many of them 

 have any connection with the ciliary nerves, for, as noted above, 

 they are frequently found isolated from the main nerves, or em- 

 bedded singly 01 in small groups in the muscles, or even on the 

 nerve to the rectus internus, from which nerve there is no visible 

 connection with the eye. If, then, they belong to the sympathetic 

 system they must be vasomotor cells. But that there should be 

 such an abundance of vasomotor cells in this region in Triton .is 

 exceedingly improbable. 



If these cells are not sympathetic cells, it remains only to inter- 

 pret them as muscle-sensory cells. This is, perhaps, a hazardous 

 suggestion, for it would necessitate the presence of afferent fibers 

 in the oculomotor root, which ranks with the ventral spinal roots 

 as purely motor. But in my paper on Amblystoma I have 

 described a ganglion on the root of the first spinal nerve which 

 has no dorsal root, and, so far as I have been able to determine, it 

 has no fibers which reach the skin. I have considered this latter 

 as a vestigial spinal ganglion, since it does not occur in all speci- 

 mens. Yet there is no proof that it is functionless. In T. 

 tasniatus, on the other hand, nerve cells occur on the oculomo- 

 torius of every specimen which has come under my observation. 

 They are much more numerous, also, than similar cells are on the 

 oculomotorius of larval Amblystoma, and since they are constant 

 in occurrence they must be of physiological significance. 



But whatever the significance of these cells may be, it is note- 

 worthy that, provided the muscle-sensory fibers oT these amphib- 

 ians are meduUated, the mm. rectus internus and obliquus inferior 

 of Amblystoma, and in some instances the mm. recti superior and 

 inferior also, are completely cut off from sensory innervation unless 

 there are afferent fibers in the oculomotor root. The same is true 

 of the mm, rectus internus and obliquus inferior in some speci- 

 mens of Triton. 



