tinually growing downwards from this coronary cushion to meet the demands of attrition; and if hindered from coming into contact with the earth, would increase to an indefinite length. The fibres of the horny sole follow exactly the same direction as those of the wall, and are destined, like them, to come more or less in contact with the ground, and support the weight of the body. They vary in length, being shortest towards the middle of the sole, and longest at their junction with those of the wall. At this part the sole is equal to the wall in thickness. Unlike the wall fibres, however, those of the sole only attain a certain length, when the horny matter of which they are composed dries and fractures like the human hair. By this means the sole seldom, if ever, becomes abnormally thick in a state of nature, and the loose flakes that are continually forming are not only active agents in retaining the moisture necessary for maintaining the elasticity and proper development of horn, but also play the part of so many pliant defences to guard the plantar surface of the hoof from injury by extraneous substances, with which it is always coming in contact.
The frog is a most important organ. It is analogous to the elastic pads on the foot of the dog, cat, camel, elephant, and other creatures. It is designed, like these pads, to meet the ground, diminish the jar to which the limb would otherwise be subjected, especially during violent exertion, and, by its india-rubber-like properties, prevent slipping. In conjunction with the admirably constructed vascular cushion, or 'sensitive frog,' lying above it, and contained between the wings of the pedal bone, it acts as a protection and support to the large
