HuBER, Sensojy Nci've-fibers in Visceral Nerves. 143 



servations which I have been able to make. I may state that 

 the great majority of such observations have been made on Hv- 

 ing tissue injected with a i per cent, solution of methylen blue in 

 normal salt. The tissues after the nerves were stained were fixed 

 in a saturated aqueous solution of ammonium picrate and cleared 

 and mounted in an ammonium-picrate-glycerine mixture. As 

 may readily be seen, the most serviceable preparations are ob- 

 tained from mucous membranes which may be studied without 

 further sectioning, and in which, if well stained, nerve fibers 

 may be traced for long distances, through various branchings 

 and often to their termination. 



I have previously touched on the destination of the axis 

 cylinders of many of the larger medullated fibers found in the 

 sympathetic nerves in speaking of their termination in the spe- 

 cial end-organs mentioned and of their entire ending in free 

 sensory endings. It is particularly the latter, the more 

 common form of termination, that I desire to bring to your 

 notice. When it is possible to trace such medullated fibers to 

 their endings, it may be observed that before terminating they 

 undergo repeated division before losing their medullary sheaths, 

 such division taking place at the nodes of Ranvier, the resulting 

 branches diverging at angles which vary greatly. This division 

 takes place mainly in the mucosa of the hollow organs in which 

 the nerve terminates. (In this general discussion reference is 

 not had to the intestinal canal unless especially mentioned). 

 The extent of this division is, I believe, greater than is gener- 

 ally supposed, and may, therefore, receive fuller consideration. 

 It may best be studied in preparations occasionally obtained, in 

 which, owing to the precariousness of the methylen blue meth- 

 od, only a few, perhaps only one large axis cylinder with its 

 many branches and endings, is stained in a given region, and if, 

 perchance, such a fiber is stained to its finest terminal branches, 

 the extent of this division is surprising, even to one familiar 

 with methylen blue preparations. 



I have reproduced in the accompanying figure the medul- 

 lated and non-medullated branches of one afferent fiber, found 

 in the mucous membrane of the urethra of a female cat, just 



