Others of the papillæ 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 their 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 pigmented, _horny, fibrous material_. 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