CARPENTER: DEVELOPMENT OF THE OCULOMOTOR NERVE. 149 



A considerable amount of evidence as to the nature of the ciliary 

 ganglion in mammals has been derived from the employment of degener- 

 ation methods. To appreciate the significance of the results obtained, 

 it must be borne in mind that in a typical sympathetic ganglion (one of 

 the gangliated sympathetic cord) the motor neuraxons of the white 

 ramus (" pre-ganglionic fibres"), originating from cells within the central 

 nervous system, pass into the sympathetic ganglia, and end in peri- 

 cellular baskets of fine fibrils about the sympathetic cells. From the 

 latter are given off, peripherally, non-medullated neuraxons ("post- 

 ganglionic fibres"), which make up the pale sympathetic nerves. These 

 neuraxons, together with the sympathetic ganglion cells with which 

 they are connected, form, consequently, the terminal link in a chain of 

 neurons. 



The investigations of Bach ('96) on the rabbit show that removal of 

 the iris and ciliary body, to which the short ciliary nerves are distrib- 

 uted, results in a modification of the cells of the ciliary ganglion, while 

 those of the nidulus of the oculomotor nerve remain normal. Apolant 

 ('96, '96 ') cut the oculomotor nerve of young cats near its root. The fine 

 medullated neuraxons passing to the ciliary ganglion degenerated periph- 

 erally as far as the cells of that ganglion, while these cells, together 

 with the short ciliary nerves, remained unaltered. Bumm (:00) con- 

 firmed Apolant's results. After injury of the intrinsic eye muscles and 

 the nerves distributed to them, nearly all the cells of the ciliary ganglion 

 undergo changes (Marina, '98, '99), but, as shown by the further experi- 

 ments of Marina, and by those of Fritz ('99), destruction of the cornea 

 is also followed by a slight degeneration of some of the cells of the 

 ciliary ganglion (one-eighth of the entire number, according to Marina). 

 From this, both writers conclude that the ganglion is a mixed one, 

 being largely motor-, but also to some extent sensory in function. 

 Fritz ('99) infers that the ciliary ganglion is connected with the sym- 

 pathetic system from the fact that changes in the cells of the ganglion 

 occur upon extirpation of the cervical sympathetic. Bumm (:00) is 

 also of this opinion, since the cutting of the ciliary nerves in the cat 

 results in the atrophy of only four-fifths of the cells of the ciliary gan- 

 glion. He considers the cells affected to be those of peripheral neurons, 

 while the cells which remain unaltered are probably connected with the 

 sympathetic system. 



The study of degeneration preparations shows, then, that at least the 

 majority of the mammalian ciliary -ganglion cells and their processes, 

 the short ciliary nerves, may be considered the terminal neuraxons of a 



