552 THE SYMPATHETIC SYSTEM OF NERVES, BY DR. S. MAYER. 



trunk of the sympathetic, while in the spinal nerves about one- 

 third run towards the centre, and about two-thirds towards the 

 periphery. The fibres proceeding from the cerebro-spinal organs 

 run, not only through the sympathetic ganglia, but they are 

 also continuous with its cells, as Courvoisier has again recently 

 demonstrated by researches made upon sections of the rami 

 communicantes, with subsequent examination of the resulting 

 degenerative processes. On section of the rami communicantes 

 the greater part of the fibres of the sympathetic portion of the 

 trunk undergoes degeneration ; and the cells also participate in 

 the processes of degeneration in a peculiar mode that has been 

 described by Courvoisier. The spinal segment of the section 

 degenerates only in small part. According to Courvoisier, the 

 degeneration in the fibres of the sympathetic stump of the 

 rami communicantes is primary and tertiary ; that is to say, in 

 the latter case, after attacking the cells, is transferred to the 

 fibres proceeding from the cells. As regards the nature of 

 the fibres of the sympathetic, the view that the sympathetic 

 nervous system is characterized by the occurrence of medullated 

 fibres of much finer calibre than those of the cerebro-spinal 

 system, is now given up. It is undoubtedly true that fine dark- 

 edged fibres of medium size are abundantly and widely dis- 

 tributed, as well as the various kinds of non-medullated fibres. 

 In regard to the character of these structures, the reader is 

 referred to the third chapter of this work. The so-called 

 transitional fibres of Courvoisier, which alternately cast off and 

 resume their medullary sheath, I have not unfrequently seen 

 in the sympathetic of the Frog. Whether these fibres are to 

 be regarded as artificial products, as some authors maintain, 

 can only be determined by further investigation. 



As regards the mode in which the fibres of the sympathetic 

 nervous system are distributed, their rough anatomy, the course 

 and relation of the principal trunk, the number of ganglia, etc., 

 will be found described in manuals of systematic anatomy. 

 Dating from the excellent researches of Remak and Bidder, 

 sympathetic ganglion cells have been discovered in great 

 numbers in almost every organ of vegetative and generative 

 life. 



In the apparatus of circulation, the heart contains ganglion 



