GANGLIONIC NERVES. 



415 



however, exist in the spinal ganglia as Fig- 288. 



small as any found here. On the other 



hand, some of these measure even ? J^ 



of an inch. They are mostly unipolar, 



and very rarely bipolar. Apolar cells 



are also more abundant than in the spinal 



ganglia. (Fig. 289.) 



3. The ganglion-fibres are of the finest 

 kind, YOTFOO to SIHJS of an inch in diame- 

 ter. They are dark-bordered, but pale. 

 They constitute a large proportion of the 

 sympathetic trunk, and its branches, but 

 are in no respect peculiar to it, as has 

 been shown (p. 429). The existence of 

 these fibres does not confer a special func- 

 tion on the sympathetic nerve, and which 

 does not exist elsewhere; though they 

 may manifest a peculiar function wher- 

 ever found, whether in the sympathetic 

 or the spinal nerves. 



The " fibres of Kemak" which have 

 already been described, also enter into 

 the structure of the peripheral branches 

 of the sympathetic nerves; and some- 

 times constitute three-fourths or even 

 nine-tenths of the branch (p. 429). 



A great number of ganglia also occur 

 on the peripheral branches of the sympa- 

 thetic, some of them of merely micro- 

 scopic dimensions. They have a struc- 

 ture like that before described, and the ganglion-cells give off new 

 fibres, so that the emergent branches always contain an increase of 

 them. In these also many of the cells are apolar. 



How are the fibres of the sympathetic finally distributed? 



1. The fibres terminate by division in some cases; e. g. the nerves 

 of the spleen, in the Pacinian bodies of the mesentery, in the nerves 

 temporarily existing in the uterus of the rodentia, and those of the 

 dura mater on the meningeal arteries, &c. 2. There are free ter- 

 minations of the fibres; as in the Pacinian bodies, and the mesen- 



Sixth thoracic ganglion on the 

 left side of the sympathetic nerve 

 of the rabbit, seen from behind, and 

 treated with soda. (Magnified 40 

 diameters.) T2. Trunk of the sym- 

 pathetic. He, He. Kami commu- 

 nicantes, each dividing into two 

 branches. Spl. Splanchnic nerve. 

 8. 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, g. Ganglion-cells. 

 (Kolliker.) 



