252 



NERVOUS SYSTEM. 



[sect. 123. 



Fig. 105. 



undoubtedly resemble, in a certain respect, tbe latter, which are, 

 in like manner, formed of the ganglionic fibres of the spinal 



ganglia, and of fibres which spring from 

 the cord; but the sympathetic nerves 

 differ particularly in this, that they 

 possess a much larger number of inde- 

 pendent elements of ganglia and of 

 ganglionic fibres, and form much more 

 numerous anastomoses with one another. 

 While, therefore, it may be right to con- 

 sider them apart, in an anatomical view, 

 we are not warranted in holding; them 

 as altogether peculiar, seeing that all 

 nerves fundamentally agree in their 

 chief elements, some cerebral nerves 

 {vagus, glosso-pliaryngeus), even exhi- 

 biting numerous peripheral ganglia; 

 and that, moreover, comparative anatomy 

 indicates their derivation from the spinal 

 nerves, and that physiology shows them 

 to have no speciality in function. 



Sixth thoracic ganglion of the 

 left side, from the sympathetic of 

 the rabbit, seen from the posterior 

 side, treated with caustic soda, and 

 magnified 40 times. T. 2. Trunk 

 of the sympathetic nerve. R. c. 

 R. e. Rami communicantes, both 

 splitting into two branches. Spl. 

 Splanchnicus. S. Twig of the 

 ganglion, with two thicker and 

 some finer fibres, probably going 

 to vessels, g. Ganglion-globules 

 and fibres, joining the trunk of 

 the main cord. 



§ 123. Cord of the Ganglionic Nerves, 

 Nervus Sympathicus. — The sympathetic 

 nerve in man is a whitish or white nerve, 

 whose dark-bordered tubes generally run 

 parallel to each other, without dividing 

 or anastomosing, some of them mea- 

 suring o - oo25'" to 0-006'" or more, 

 others only o , ooi2 w to o - oo25"' in 

 diameter. These finer and thicker fibres 

 run partly intermingled with each other, partly in separate 

 bundles, alongside each other, which latter arrangement especially 

 prevails in the neighbourhood of the ganglia of the main cord, 

 and in these ganglia themselves. In structure, the ganglia 

 agree generally with the spinal ganglia. Each of them consists, 

 1, of nerve-fibres which pass through it, going from one part 

 of the trunk to another; 2, of a certain number of fine tubes 

 arising in the ganglion; and 3, of numerous ganglion-cells. 

 Moreover, the rami communicantes enter into the ganglia, and 

 branches pass peripherally out of them. The ganglion-cells in the 

 sympathetic (fig. 105, B) present essentially the same relations as 



