NERVES. 3G3 



sympathetic cord itself, and the splanchnic nerves; the cardiac 

 nerves are almost entirely formed of tubular fibres. In all 

 these nerves the tubular fibres are observed to be of smaller 

 diameter than they are in those which are distributed to the 

 voluntary muscles. 



In consequence of the great difference which exists be- 

 tween the structure of the tubular nerve fibre and that of 

 the gelatinous nerve fibre, it has been a matter of doubt 

 with some observers whether the latter should be regarded 

 as a true nerve fibre or not. 



The following is a brief enumeration of the various ana- 

 tomical and microscopical facts hitherto recorded both in 

 favour of and opposed to the opinion of the nervous character 

 of the gelatinous filaments just described. 



The chief structural considerations which may be urged in 

 favour of the opinion that the nucleated filaments associated 

 with the various nerves of the sympathetic system are true 

 nerve filaments are 



1st. The origin of the gelatinous filaments from the ganglia 

 of the sympathetic, as first distinctly affirmed in the researches 

 of Volkmann and Bidder. * 



2nd. The tubular character of these filaments, as shown 

 by T. Wharton Jones, f 



3rd. The periphral distribution of the gelatinous filaments, 

 as asserted by many observers, but particularly by Bidder, 

 who even states that he succeeded in counting their number 

 in the transparent septum of the auricles of the frog's heart. 



4th. The peculiar structure of the ganglion csecum, dis- 

 covered by Mr. T. Wharton Jones, in connexion with one 

 of the ciliary nerves of the dog. j 



5th. The variable yet fixed proportions of gelatinous and 

 tubular fibres occurring in different nerves, as described 

 especially by Henle. 



6th. The occurrence, as stated by Todd and Bowman, of 



* Die Selbstandigkeit des Sympathisken Nervensystems durch Ana- 

 toniische Untersuehungen nachgewiesen Yon J. H. Bidder und A. W. 

 Volkmann. Leipsig, 1842. 



f Lancet, April 24th, 1847. J Lancet, November 14th, 1846. 



G G 



