661 ANATOMY AND PHYSIOLOGY OF THE HORSE'S FOOT. 
cles, as well as the hairs springing from them, acquire an 
enormous development, particularly towards the heels in 
certain breeds of horses; the sebaceous glands are propor- 
tionately enlarged, and the perspiratory ones decrease. The 
object of this is evident enough. The lower parts of the 
limbs being at certain seasons, in particular climates, exposed 
to wet and cold, as well as the prejudicial action of certain 
soils, they have been protected, in addition to a thicker skin, 
by this close covering of long coarse hair, and larger and 
more numerous oil-glands whose secretion not only keeps the 
tegument flexible, particularly in the hollow of the heel, where 
there is most motion, but also provides it with an unctuous 
coating that repels the wet, while the long hair prevents too 
rapid evaporation. This thickness of the integument also 
serves to explain why wounds and abscesses in this region 
often assume such a serious character. 
Such are the general features of the skin of the foot until 
we reach that part designated the “ coronet/’ where the wall 
of the hoof originates. In order to examine the modifications 
to which it now becomes subjected, it is often advantageous 
to submit the foot, with the hoof thereon, to prolonged 
maceration in water, so as to be able readily to separate the 
latter from the structures it contains. 
If this removal of the hoof has been carefully effected, the 
display of organization that meets the eye is truly marvellous, 
and one that never fails to excite a strong feeling of admira- 
tion in the comparative anatomist, no matter how frequently 
he may perform this operation : more particularly is this the 
case if the vessels of the foot have been previously injected 
with some fine colouring matter. 
We then perceive that at the origin of the hoof wall, or 
where the hair ceases to grow, the skin becomes somewhat 
suddenly thickened to form two convex enlargements of 
unequal volume and convexity, extending around the space 
comprised between the lower end of the coronary or small 
pastern bone, and the upper border of the os pedis, and 
lying one above the other. The first and uppermost of these 
(fig. 12, a) is not markedly salient, and starts out gently from 
the line where the hair terminates, passing round as a light 
pink band in a circular manner towards the heels, its greatest 
width being in front ; and gradually diminishes its superfi- 
cies, until it attains the points or bulbs of the cartilages, 
where it abruptly expands to incorporate itself with the 
tegumentary membrane covering these and the plantar 
cushion. Above, as we have just remarked, it is only limited 
by the hair, but below it is separated throughout its extent 
