ON THE GANGLIONS AND SYMPATHETIC NERVES. 503 



mists and physiologists on the texture and function of gan- 

 glions, may be referred to two principal ones differently 

 modified: some, regarding them simply as condensed plexuses, 

 consider the nerves which depart from them, only as distant 

 divisions of the spinal and cranial nerves; others, considering 

 the ganglions as special nervous centres, consider the nerves 

 which emanate from them as independent of the cerebral sys- 

 tem. We shall see that these two opposite systems ought 

 to be combined and mutually modified. 



794. The inferior animals, that is to say, the radiata, the 

 mollusca, and the articulata, have nervous enlargements which 

 have been assimilated to the ganglions of the vertebrata. But 

 in the invertebral animals the same nerves belong to all kinds 

 of organs and functions, whilst in the vertebrata the great 

 sympathetic nerves (and to a certain degree, the pneumo-gas- 

 tric nerves), belong especially to the organs of vegetative func- 

 tions. Weber has compared the spinal ganglions of the ver- 

 tebrata to the ganglions of the inferior animals. 



In vertebral animals, which alone have true nervous gan- 

 glions comparable to those of man, we see these ganglions 

 augment, especially those of the sympathetic nerve, and the 

 pneumo-gastric nerve diminish astheencephalon becomes de- 

 veloped, so that fishes have the smallest sympathetic nerve, 

 and the largest pneumo-gastric, and vice versa in the mammalia, 

 as if the vegetative functions ought to be farther removed 

 from the influence of the encephalon, in proportion as this 

 organ is less t subject to instinct. 



795. The ganglions have been divided into several kinds 

 by those who have described them with the greatest accuracy. 

 Scarpa divides them into simple or spinal, and into compound. 

 Weber divides them into auxiliary ganglions (de renforce- 

 ment,) which are those of the spinal nerves, and some of those 

 of the cranial nerves; and into ganglions of origin: these are 

 those of the sympathetic nerve, to which he joins the orbitary 

 and the maxillary. Ribes* divides the ganglions into three 



* Expose sommairede quelques recherches anat. phys. et pathol., in the Mem. 

 de la soc. med. cumulation, vol. viii. 

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