NO ENDS TO BE DEMONSTRATED. 173 



tliat there is not such a tiling as a true cvrl to any 

 nerve-fibre. I must, however, admit that almost all 

 the observations which have been made in Germany 

 during the last few years are opposed to this view. 

 Memoir after memoir has been published for the 

 purpose of proving that nerves exhibit terminal ex- 

 tremities in several motor and sensitive organs. As 

 investigation proceeds, this controversy becomes more 

 interesting and exciting. Although my opponents 

 are many and powerful, the facts in favour of my 

 own view are now very numerous and almost every 

 new investigation I attempt enables me to add more 

 to the number. Moreover, my conclusions rest upon 

 observations upon many difierent tissues and organs 

 not only of vertebrata, differing widely from one 

 another, but of numerous invertebrate animals. I 

 cannot therefore yield. I am quite convinced that 

 numerous specimens I have made fully justify me 

 in maintaining the general proposition that in all 

 cases the terminal disti'ibution of nerves is a plexus, 

 network, or a loop, and hence that in connection 

 with every terminal nervous apparatus there must be 



Pfliiger has arrived at the conclusion that the nerves distri- 

 buted to the salivary glands end by exceedingly fine filaments 

 which pass into the epithelial cells and become connected with 

 them or their bioplasts (nuclei) ; but I do not think that in 

 this organ any nerve-fibres pass beyond the surface of the con- 

 nective tissue upon which the secreting bioplasts lie. I have 

 never been able to convince myself that nerves ]3ass to the epi- 

 theUal cells in any of the situations indicated, nor have I seen 

 any preparations at all conclusive. On the other hand there 

 are many facts opposed to this view. Upon the whole, the 

 evidence, so far, is strongly in favoiu' of terminal networks be- 

 neath the epithelium of such tissues as mucous membrane and 

 secreting glands. And as the act of secretion, — the production of 

 peculiar compounds by bioplasm differing entirely from the ma- 

 terials out of wliich they were made, — is certainly performed in 

 many cases without nervous agency, much stronger evidence 

 than any yet advanced ought to be adduced before the conclu- 

 sion that nerves act directly upon the secreting cell is accepted. 



