NERVES OF THE TESTES. 163 



easily satisfied himself of the presence of an epithelial invest- 

 ment on the tubuli seminiferi, by treatment with nitrate of silver. 



As regards the nerves proceeding from the plexus spermaticus 

 internus, no observer, up to a very recent time, was able 

 to follow them to their ultimate distribution. Quite lately, 

 however, Letzerich * has described the mode of termination of 

 the nerves in the testes of Mammals and of Man. 



In fresh seminiferous tubules, or in those that have been 

 macerated for twenty-four hours in a solution of chromic acid, 

 containing from l-20th to 1-2 5th per cent., Letzerich saw nerve 

 fibrils that penetrated the connective-tissue layer and mem- 

 brana propria, and terminated between this membrane and the 

 first layer of cells in a dark granular substance. The latter 

 consisted of a granular, lustrous, and irregularly shaped mass 

 of protoplasm, into which the nerve penetrated, ending in fresh 

 preparations in a dull, but in slightly hardened preparations in 

 a brightly refracting, nodule. The nerve sheath did not pene- 

 trate the protoplasmic mass, but appeared to be continuous 

 with a membrane of extreme tenuity that invested it, so that 

 the proper termination of the nerve fibril seemed to be formed 

 by a relatively short and broad axis-cylinder, with usually an 

 excentrically situated round and bright bulb. 



These which, if accurate, are certainly very valuable observa- 

 tions, have not as yet been corroborated. I have hitherto in 

 vain attempted to do so myself. 



* Virchow's Archiv, Band xlii., p. 510. 



