THE FOOT OF THE HORSE. 47 



tremity of the digit. It answers to the same natural purpose as 

 the nail in man, by protecting the sensitive parts beneath. It 

 is united most intimately with the internal tissues by the in- 

 terlocking processes of the surfaces in contact, and is made up 

 of three portions — the wall, sole and frog. 



The Wall. — The wall is that portion visible when the foot 

 rests on the ground, the middle of which is termed the toe, 

 the adjoining fronts of face are the inside and outside toes, 

 while the side regions are the quarters, the back extremities are 

 the heels, which fold underneath and terminate in the bars. 

 These parts are all continuous, diminishing in height and thick- 

 ness from toe to heels, and all are lined with the horny leaves 

 referred to. The bars are separated from the frog by lateral 

 excavations called commissures, until they gradually fuse into 

 sole. They form a lateral brace to the heels, limiting expan- 

 sion and opposing contraction in these parts. The outside 

 of the upper border is hollowed out, forming the cutigeral 

 cavity of the coronary cushion and perioplic ring. 



The Sole. — The sole incloses the hoof on the ground sur- 

 face, between the wall and bars, with which it is united through- 

 out its extent. Its upper surface corresponds with the sen- 

 sitive sole, showing the pores receiving the velvety tufts, and its 

 external face is more or less concave according to circumstances. 

 It IS a thick horny plate, scaling oft' after a certain natural 

 growth, and is designed to cover and protect the internal foot. 



The Frog. — Between the A shaped angle formed by the 

 inflection of the bars at the heels, the frog — a prominent mass 

 of spongy horn — is lodged. It is wedge-shaped, with its point 

 near the center of the sole, to which it closely adheres along 

 its lines as thev diverge backward, where it becomes contin- 

 uous with the coronary band. The frog is separated into two 



