4 
48 STRUCTURE OF THE SKIN, “= 
same kind is found in the matrix or receptacle of the growing 
roots of nails, hoofs, horns, &c. which are only modified forms 
of epidermis. Imbedded in the substance of the cutis we — 
find, in most situations, the perspiratory glands (fig. 7, ee), by — 
which the watery fluid that is continually being exhaled from — 
the skin, is separated from the blood (§ 371) ; these send forth — 
their secretion by canals (g h), which traverse the epidermis — 
in a corkscrew-like manner, and then open upon its surface | 
by oblique valvular orifices. In the Cutis, also, are lodged — 
the hair-follicles (§ 38), which are really pits or depressions — 
of its surface, with a vascular papilla at the bottom of each, 
supplying nutriment for the abundant development of the 
cells in which the hair originates, as will be presently 
described. Wherever the hair-fol- — 
licles occur, there do we also find 
sebaceous follicles (fig. 8, a a); these 
are peculiar glandule, secreting fatty 
matter, which is poured into the hair- — 
canal, so as to come through it to the 
surface of the epidermis ; and the use 
of this secretion, which is particularly 
abundant in the dark skins of the 
natives of warm climates, is to pre- 7 
vent the cuticle and the hair from 
being too much dried up by exposure 
to air—The surface of the Cutis is 
covered by a layer of basement-mem- — 
brane (§ 31), which is not traversed — 
either by blood-vessels, nerves, or 
absorbents ; so that none of these 
pass into the epidermis which lies on 
its outer side, 
88. The Spidermis, otherwise 
termed the cuticle, or “scarf-skin,” is 
Tur po he Homan composed of numerous layers of nu- 
Scatr;—a a, sebaceous glands; cleated cells ; of which we find those 
», ahair, with its folliclee. + immediate contact with the base-— 
ment-membrane to be nearly spherical ; those a little removed — 
from it to be rendered polygonal by the mutual pressure | 
their sides ; those nearer the outer surface to be flattened, — 
and this in an increased degree, as we pass from within 
Pa 
wed 
