SYMPATHETIC NERVOUG SYSTEM. 425 



tain fibres in the end attached to the spinal . nerve become 

 degenerated, while others retain their anatomical integrity. 

 This shows that, in all probability, the cells to which the 

 degenerated fibres belong are in the sympathetic ganglia, 

 and that the perfect fibres belong to the cerebro-spinal sys- 

 tem. On the other hand, in the end attached to the sympa- 

 thetic ganglia, there are degenerated fibres which belong 

 to the spinal system, and perfect fibres attached to the sym- 

 pathetic cells. According to these observations, in frogs, 

 the fibres belonging to the spinal nerves constitute about 

 two-thirds of the communicating branches, one-third being 

 derived from the sympathetic system. In rabbits, the pre- 

 ponderance of the cerebro-spinal fibres is not so great. 1 



While the branches of the sympathetic contain a large 

 number of the ordinary medullated fibres, such as are found 

 in the cerebro-spinal nerves, they also present numerous 

 fibres of Remalc, and fine fibres, from 10 ^ 00 to 6 ^ QO of an 

 inch in diameter, which are regarded by Kolliker as true 

 efferent fibres from the sympathetic ganglia. 2 "With regard 

 to the fibres of Reinak, we have nothing to add to what we 

 have already stated under the head of the general structure 

 of the nervous system. 3 These points, with the fact that 

 most of the terminal filaments of the sympathetic are con- 

 nected with nerve-cells in the substance of the different tis- 

 sues, constitute the most important anatomical peculiarities 

 of the sympathetic nerve-fibres. 



With regard to the cells, which constitute the character- 

 istic anatomical element of the sympathetic ganglia, we shall 

 have little to say, as their peculiarities at present seem to be 

 of purely anatomical interest. They are generally rounded, 

 ovoid, or pear-shaped, with a nucleus, generally clear, and a 



1 COURVOISIER, Beobacldungen tiber den sympathvsclien Qrranzstrang. Archiv 

 fur microscopische Anatomic, Bonn, 1866, Bd. ii., S. 30, et seq. The method 

 adopted in these investigations is the one already referred to, employed by "Wal- 

 ler. (See page 80.) 



8 KOLLIKER, Elements d'histologie humaine, Paris, 1868, p. 426. 



3 See page 24. 



