THE NERVOUS SYSTEM 183 



are much smaller in Salamandra, it is interesting to note that nerve- 

 cells do occur along the commissure joining the two sides, so that it 

 is easy to see how the unpaired condition has arisen. Heidenhain 

 describes the ganglion in the male only, but no appreciable difference 

 between the sexes has been noticed in Salamandra. 



The sympathetic nerve for the hind-limb leaves the ventral strand 

 at the plexus around the iliac artery. Fine fibres leave both the an- 

 terior iliac ganglia and entwine the artery, finally uniting to form a 

 single strand at the edge of the kidney. From about the point at 

 which the longitudinal nerve strand divides into dorsal and ventral 

 portions as described above, i.e. at about the twelfth or thirteenth 

 ganglion, a fine nerve is given off which passes laterally, and appar- 

 ently supplies Miiller's duct and the Wolffian duct. It is larger in the 

 female. There appears to be a nerve plexus around these ducts but 

 the details have not been elucidated. 



(iii) The caudal -portion is relatively simple and consists of a double 

 nerve chain lying along the caudal artery. The ganglia are approxi- 

 mately segmental in arrangement. Anastomoses between the two 

 sides are fairly frequent — otherwise there are no special features to 

 note. 



(i) The cephalic portion. After receiving the ramus communicans 

 from the first spinal nerve, at about the point where the systemic 

 arches join to form the dorsal aorta, the sympathetic chain follows 

 each systemic arch around the pharynx, remaining rather towards 

 the posterior side of the vessel. On reaching the point where the 

 A. pharyngea ascendens is given off the nerve is deflected along it, 

 and a portion enters the hyomandibular trunk of the facial nerve close 

 to the point where the ramus communicans from NN. IX and X is 

 received, and where the R. alveolaris is given off. At this point also 

 a few nerve-cells occur (cf. p. 146). Another branch of the sympa- 

 thetic crosses over the systemic arch and follows the A. petrosa 

 lateralis into the antrum. It has not been determined precisely what 

 happens to it, but presumably it enters the trigeminus ganglion, 

 and, passing by way of the ophthalmicus profundus and the ramus 

 communicans V ad III, reaches the ciliary ganglion on the oculo- 

 motor nerve. This point, however, has not been definitely estab- 

 lished. The portion of the sympathetic passing round the systemic 

 arch also appears to be connected with the pharyngeal rami of the 

 branchial branches of the vagus nerve — in fact this has been de- 

 scribed by Druner. The presence of nerve-cells along certain rami 

 of the cranial nerves, and in the ganglion copulare and the palatine 

 ganglion, has already been noted (cf. pp. 141, 145, 150-2). 



