GENEKAL OBSERVATIONS 47 



for its nourishment upon the indirect supply it receives 

 from the vessels of the corium. The need for extreme 

 vascularity of the corium is further explained when we call 

 to mind the constant proliferation and casting off of the 

 cells of the epidermis, the growth of the hairs, the pro- 

 duction of the horn of the hoof, and the work performed by 

 the numerous sweat and other glands. 



Others of the papillfe contain nerves, ending here in 

 tactile corpuscles, or continuing, as we have mentioned 

 before, to ramify as fine fibrils in the rete mucosum of the 

 epidermis. 



The Hairs are growths of the epidermis extending 

 downwards into the deeper part of the corium. Each is 

 developed in a small pit, the Hair Follicle, from the bottom 

 of which it grows, the part lying within the follicle being 

 known as the Root. It is important to note tlieir structure, 

 as it will be seen later that they bear an extremely close 

 relation to the horn of the hoof. 



Under a high power of the microscope, and in optical 

 section, the central portion of a hair is tube-like. In some 

 cases the cavity of the tube is occupied by a dark looking 

 substance formed of angular cells, and known as the 

 Medulla. The walls of the tube, or the main substance of 

 the hair, is made up of a i^igmented, horny, fibrous inatcrial. 

 This fibrous structure is covered by a delicate layer of 

 finely imbricated scales, and is termed the Hair Cuticle. 



The root of the hair, that portion within the follicle, has 

 exactly the same formation save at its extreme end. Here 

 it becomes enlarged into a knob-like formation composed 

 of soft, growing cells, which knob-like formation fits over 

 a vascular papilla projecting up in the bottom of the 

 follicle. 



We have already stated that the hairs are down-growths 

 of the epidermis. It follows, therefore, that the hair 

 follicles, really depressions or cul-de-sacs of the skin itself, 

 are lined by epithelial cells and connective tissue. So 

 closely does the epidermal portion of the follicle invest the 

 hair root that it is often dragged out with it, and is known 



