NERVES OF MAMMA I I A 



183 



Section of sixth Intercostal with communicating branch to 

 sympathetic. Rabbit (mag. 60 diam.). lxxvh". 



to the coccyx : anteriorly, or above, they pass to ganglions and 

 plexuses, within, or 

 about, the cranial 

 cavity ; below or 

 behind, they con- 

 verge and unite, 

 generally, in a ter- 

 minal ' coccygeal ' 

 ganglion. In their 

 course the cords 

 cross, ventrally, the 

 issuing trunks of 

 the spinal nerves, 

 with which they are 

 connected by short 

 threads, including 

 grey and white fila- 

 ments, and there 

 usually swelling into ganglions. The grey or gelatinous thread 

 is most probably a contribution from the ganglion to the myelonal 

 nerve, the white thread is sent 

 from the nerve to the sympa- 

 thetic ganglion : it consists of 

 tubular nerve-fibres, and these 

 predominate in the ' rami 

 communicantes ' of the rabbit 

 and cat. 2 Under a power of 

 sixty diam. after addition of 

 dilute solution of soda Drum- 

 mond found such fibres con- 

 tinued mainly from the mye- 

 lonal end or origin, fig. 138, 

 C, of an intercostal nerve, and 

 converging to form the com- 

 municating branch, RC, with 

 the sympathetic ganglion. A 

 few filaments, a, a, disappear 

 among those of the intercostal 

 nerve rather in the direction 

 of its outward course. Traced 

 to the sympathetic ganglion, 

 as in fig. 139, they diverge, 



Fourth thoracic ganglion, with course of fibres received 



by the connminioatiiig branch, c, from the myelon. 



(Mag. 70 diam.) lxxvu". 



lxxvii". p. 44G. 



