14 S. B. VINCENT 



cross the glassy layer from within and form a small plexus without 

 the layer in the same fashion and one then finds the leaf-like 

 expansions both within and without the layer from the same 

 fiber. Thus there can be discerned little difference save in devel- 

 opment between the two kinds of fibers (fig. 12). 



The nerve ring. To the neck of the follicle come also nerves 

 which take part in the formation of the dermal plexus (fig. 13 and 

 fig. 1). Some of them are diverted to the follicle before joining to 

 form the plexus, some send a long branch downward to the follicle 

 and another up to the plexus, others come out from the plexus 

 itself, often in groups of from three to a half dozen fibers among 

 which may be seen deeply stained medullated fibers, pale and vari- 

 cose fibers. These nerves are much smaller than those of the 

 large sensory trunk which enters the lower part of the follicle but 

 on the other hand there are many of them and they approach the 

 mouth of the follicle from all sides. With them are blood vessels 

 from the vascular plexus and many both of the nerves and blood 

 vessels go to serve the very large sebaceous glands of this struc- 

 ture. The rest run to the region just above the ringwulst, that 

 is just below the sebaceous glands, and here most of them lose 

 their myelin and encircle the hair at the level of the glassy layer. 



The nerve ring is deeper than the longitudinal ascending fibers, 

 many of which pass over it. The nerves which form it often 

 divide once before beginning their circuit and the two branches 

 sometimes take opposite directions, but there is no further divi- 

 sion until they have nearly or quite completed the circle; then 

 they ascend and break up into what looks like an arborization 

 in the conical body. From this brush of fibers whose ends are 

 cut across in a longitudinal section may often be seen fibers 

 running up to the surface of the skin again. I have never seen 

 the longitudinal fibers take any part in the formation of the 

 nerve ring. 



The course here described is for the strong deeply medullated 

 fibers. As these run down from the surface they are accom- 

 panied by paler fibers and varicose fibers, as has been said, but 

 their course I could not follow after they were lost in the intri- 

 cate ring plexus. 



