STRUCTURE OF THE SKIN. 
48 
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) y 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 glandulse, 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¬ 
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. 
38 . The Epidermis , otherwise 
Fi g termed the cuticle , or “ scarf-skin,” is 
„ _ -jnr composed of numerous layers of nu- 
Thin Section of the Human r J 
Scalp ;— a a, sebaceous glands ; cleated Cells j Ot which We find tllOSe 
b, a hair, with its follicle c. j mmec q a t e contact with the base¬ 
ment-membrane to be nearly spherical; those a little removed 
from it to be rendered polygonal by the mutual pressure of 
their sides; those nearer the outer surface to be flattened, 
and this in an increased degree, as we pass from within 
