THE NERVOUS SYSTEM. 



477 



possess a much greater number of Independent elements, of 

 ganglia and ganglionic fibres, and enter into much more nume- 

 rous anastomoses with each other. Consequently, although we 

 appear to be justified from an anatomical point of view, in con- 

 sidering the ganglionic nerves by themselves, still they must not 

 be regarded as something altogether peculiar, seeing that, essen- 

 tially, every nerve exhibits the same principal elements, and some 

 cerebral-nerves, vagus, glossopharyngeal, possess even numerous 

 peripheral ganglia; and moreover, because comparative Ana- 

 tomy shows that they arc produced from the spinal nerves, and 

 Physiology the absence of peculiar functions in them. 



§ 124. 



The principal trunk of the gang- 

 lionic nerves, (nervus sympathicus). 



The n. sympathicus in man appears 

 as a whitish, or white nerve, the 

 dark-bordered fibres of which usually 

 run parallel with each other, without 

 divisions or anastomoses, some measur- 

 ing 0025 — O'OOS'" or even more, 

 and others not more than - 0012 — 

 - 0025'". These finer and coarser 

 fibres are partially intermixed, partly 

 disposed more in a fascicular manner, 

 the latter being the case near the 

 ganglia of the main trunk and in that 

 part itself. The structure of the ganglia 

 is, in the main, similar to that of the 

 spinal ganglia. Each of them consists : 

 1. of perforating nerve-fibres, proceed- 

 ing from one part of the trunk to the 

 other ; 2. of a certain number of finer 

 tubules originating in the ganglion ; and 



Fig. 1G1. 



3, of numerous nerve- 



Fig. 161. Sixth thoracic ganglion, on the leftside, of the sympathetic nerve of 

 the Rabbit, viewed from behind, treated with soda, and magnified 40 diam.: T. 2, 

 trunk of the sympathetic; R.c, R.c, rami communicantes, each dividing into two 

 branches; Spl., n. splanchnictts ; S, twigs of the ganglion with two stronger fibres 

 and finer filaments, probably going to vessels ; G, nerve-cells, and ganglion-fibres 

 joining the main trunk. 



