24 S. B. VINCENT 



arrangement for flooding so richly an innervated region with 

 blood some basis for such conclusions. 



One factor has yet to be mentioned — The vibrissae are, in a 

 way, secondary sexual organs. The vibrissae of the males are 

 larger and stronger. This difference is not great in rodents but 

 sufficient to attract attention and cannot be explained by greater 

 health and ^dgor on the part of the male. 



Darwin believed that the beard was first acquired as an orna- 

 ment, but Cunningham thinks that it arose in response to stimulus 

 caused by attacks about mouth and throat ('99, p. 41). In 

 animals where stroking about the head and mouth is a part of 

 courtship, these organs may contribute to the excitement. While 

 we cannot but admit that some secondary sexual characters seem 

 more intimately connected with sex functions than others, it does 

 seem probable that vascular structures such as we have described 

 in these hair follicles may share or in some way contribute to the 

 emotional excitement. The sensory quale arising from such reflex 

 excitation might serve to enhance such emotion. At any rate we 

 must face the fact that the abundant vascular supply may possess 

 an affective or emotional significance and not be entirely connected 

 with a sensory, tactile function. 



VII. SUMMARY 



The follicle of this tactile hair consists of invaginated skin 

 layers which form the outer and inner root sheath. It has be- 

 sides these a dermal sheath between whose layers are large blood 

 sinuses. The lower sinus is filled with erectile tissue and separated 

 from the upper by an outgrowth of the root sheath called the ring- 

 wulst. There are striped muscles enough to account for all the 

 movements of the hair. The follicle has a distinct and extensive 

 blood supply. It has two innervations. A large nerve bundle 

 from the infra-orbital branch of the trigeminus pierces the dermal 

 sheath in the lower part of the organ, spreads out over the inner 

 follicle in a heavy plexus and terminates chiefly in a mantle of 

 touch cells in the outer root sheath all over the follicle. From the 

 dermal plexus of the skin branches run down and form a nerve 

 ring about the neck of the follicle. Many of these fibers are also 



