364 THE SOLIDS. 



nucleated filaments very similar to the gelatinous fibres of 

 the sympathetic " in parts where their nervous character is 

 indubitable, as in the olfactory filaments, and the nerve in 

 the axis of the Pacinian corpuscle exhibits very much the 

 same appearance save that it is devoid of nuclei," * 



7th. The resemblance borne, according to the observations 

 of Schwann f , between the tubular nerve fibre in the early 

 stages of its development, in which it is described as being 

 nucleated, and the adult gelatinous fibre. 



8th. The origin of the gelatinous filaments from the cells 

 themselves composing the ganglia of the sympathetic, as the 

 observations of several observers tend to prove. 



These various facts thus briefly referred to, could they all 

 be fully depended upon, would, doubtless, make out not 

 merely a strong, but even a convincing and unanswerable 

 case in favour of the nervous character of the gelatinous fila- 

 ments : unfortunately, however, those facts, which, if they 

 could be relied upon, would be the most conclusive, are open 

 to question : such, for instance, as the periphral distribution 

 of the gelatinous filaments, their presumed origin from the 

 ganglionic corpuscles, and the asserted resemblance between 

 the tubular nerve fibre in an early stage of its development 

 and the fully grown gelatinous filament ; it will presently be 

 shown, indeed, in the observations on the growth of the 

 primitive nerve tubule that no such resemblance exists. 



Subtracting then the points referred to in the 3rd, 7th, 

 and 8th headings, no one conclusive fact remains of the posi- 

 tion that the gelatinous fibres are really nervous. 



Against the opinion that the gelatinous filaments are 

 nervous, may be urged 



1st. The positive structural identity between the gelatinous 

 nerve filament and the fibrilla of unstriped muscle, and the 

 great improbability, as a consequence, that one and the same 

 structure should have to perform two such distinct functions 

 as must necessarily belong to a muscular fibre and a nerve 

 tube. 



* Physiological Anatomy, part iii. p. 142. 



-j- See Wagner's Physiology, translation by Willis. 



