TACTILE HAIR OF THE WHITE RAT 11 



them all vaso-motor but Botezat ('97) denied this. They looked 

 to him like the intra-gemmal fibers of the touch cells and he also 

 described thickenings not unlike the knobs of the intra-epithelial 

 nerves. He thought, therefore, some of them might be sensory. 



From the position of the papilla and the little likelihood that 

 the movements of the hair can be very effective here, as well as 

 from the appearance of the fibers themselves, we believe these 

 nerves to be comparable to those which may be found in any 

 vascular structure and to be non-sensory in character. They 

 come to the papilla in many little fibers from the subcutaneous 

 tissue below and no connection can be seen with the large sensory 

 trunk which enters the side of the follicle. 



Sensory nerve. The great nerve which we have described before 

 pierces the dermal sheath together with the main artery at about 

 the lower third of the follicle (figs. 1 and 9). Here a few branches 

 which serve the lower part of the organ break away from the 

 rest, but the main portion of the nerve divides in two, one part 

 turns to the opposite side, both divide and redivide and when they 

 have crossed the sinus, surround the follicle with rows of parallel, 

 ascending bundles of meduUated fibers many of which may be 

 distinctly traced to the constriction at the neck of the follicle. 

 These bundles are not entirely separate, for fibers can constantly 

 be seen detaching themselves from one bundle to join another so 

 that it looks as though the follicle rested in a coarse cup-like 

 meshwork of bundles of heavily medullated fibers. This is the 

 outer plexus of the follicle proper and is most pronounced over 

 the superior swelling of the root-sheath. It must not be for- 

 gotten that all along the course of these bundles, fibers which 

 terminate at different levels are continually separating off; 

 but the main trunks are of such size and stain so heavily that 

 they are the most noticeable feature of the whole structure. As 

 they come to the follicle and rest thus upon it they seem to lie 

 embedded in a colorless substance which is probably the gelatin- 

 ous endoneurium of the nerve trunk. Fibers which serve the 

 upper part of the follicle bend outward at the region of the ring- 

 wulst and pass up through it. It is the bending of these nerves 

 outward which emphasizes the swelling of the root sheath here. 



