48 scn<:NTiFic hor8eshokin(}. 



external Ijrunches Ly a median cleft, each braiuli forniiiiLi: a 

 rounded elastic eminence at the heels where they cover the 

 anjj^les of inflection of the wall. The internal face of the fros; 

 is indented with jtores like the sole, and is molded to conform 

 to the body of the sensitive froi^:, havin<r a triaiiijnlar iissnre 

 divided into two channels hy n spine or ridije-like spur, called 

 the fro<2^-sta\", into and over ^^hich the sensitive frog: is bedded. 

 The frog, like the sole, exfoliates or scales otf by usage and 

 ijrowth, and is the natural buffer of a healthy foot when al- 

 lowed to come in contact with the uTound. 



Development of the Hoof. — The horny substance consti- 

 tuting the hoof of a horse is of a fibrous nature, formed of mi- 

 nute hair-like tubes, cemented together by a tenacious opaque 

 matter, taking its general color from the skin .of the iiml) to 

 which it adjoins; the inner face of the wall, however, is al- 

 ways of a light tint. The horny tissue of the hoof, being a de- 

 pendency ('>'( the skin, is tleveloped like it; that is, by cells in 

 rows and layers. The perioplic ring forms the beriople ; the 

 coronary cushion, the wall, and the velvety tissue, the sole and 

 froij. The consistence of the horn in the wall is dense, solid 

 and compact, while that of the sole and frog is of a scaly, 

 spongy nature. The growth of the wall of the hoof is constant 

 or indefinite, but the sole and frog, after attaining a certain 

 thickness, exfoliate and fall off, unless prevented by shoes froju 

 maintaining their natural flexibility. See colored plates. 



It may here be noted that the angle of wall of the hoof in 

 front varies from fortv-five to fifty-six degrees. The inner face 

 of the wall at the middle of the toe is in line with the frog-stay, 

 and in mules frequently shows a more or less prominence of base 

 toward the lower margin of wall, which corresponds to a ver- 

 tical depression in the coffin-bone, and it is not improbable that 

 it serves the same purpose as the frog-stay — to maintain the posi- 

 tion of the coffin-bone, and prevent its rotation within the hoof. 



