54 THE VETERINARY SCIENCE. 



not well to pare off too much of the barky-looking substance of 

 the sole as it helps to keep the moisture in the foot. When this 

 is taken off it allows the moisture to escape and it becomes dry- 

 and contracted. 



The Frogf is the prominent spongy horn found in the V shaped 

 notch in the back of the sole. It is wide at the back, helping- to 

 form the heels of the foot, the pointed part in the front is called the 

 apex of the frog". The under part of the frog is triangular ir* 

 shape and has a hollow in it called the cleft of the frog. There is a 

 hollow at each side of the frog, between it and the bars, 

 called the commissures of the frog. On the upper part is a 

 membrane, known as the sensitive frog, which attaches the frog 

 to the under part of the os pedis, or foot bone. This membrane is 

 simply a continuation of the sensitive sole spoken of in connection 

 with the sole. The back part of the frog is the widest part and 

 spreads out forming the heels. 



To get the best idea of the structure of the foot, get a hoof 

 and the bones of the leg as far up as the fetlock, and saw them 

 down through the centre, which will show you the exact confor- 

 mation. The shape of the hoof differs in animals — large draft 

 horses are apt to have what is termed a flat foot, while in the road 

 horses the chief trouble is what is known as contracted feet and 

 weak heels. 



CHAPTER XIII. 



THE EAR. 



THE ear of the horse is divided into several parts. The 

 inner part, or drum of the ear, is situated in the hardest 

 bone in the body, called the petrosal. The nerve which 

 passes into the drum of the ear, and gives the sense of hearing, is- 

 called the the auditory nerve. From the drum a small opening: 

 passes out into the outer part of the ear; this is the portion which 

 is seen on top of the head, and is made up of a membrane known 

 as the cartilage which gives the ear its stiffness. This cartilage 

 is covered by a fine, delicate skin, which is covered on the outside 

 by fine, short hair. Situated on the inner side of the outer ear 

 are numerous long hairs projecting outwards, the use of which is 

 to keep foreign bodies from dropping into the ear. The ear is 

 moved backwards and forwards by small muscles which are 

 attached around it. 



