172 The Hokse Industry tn New York State 



its thickness and the lenG;th of its hairs, especially around the 

 hind parts of the fetlock joints in certain breeds of horses. The 

 most important part of this envelope is that known as the coronary 

 hand. The coronary band is that portion of the skin which 

 secretes the horn of which the wall of the hoof is made. The 

 horn much resembles the nails which grow on the fingers and 

 toes of man. It is composed of hollow, cylindrical tubes, extend- 

 ing from the coronary band to the lower border of the hoof, which 

 are held together by tenanious opaque matter. 



The hoof is a box of horn, consisting of a wall, sole and frog, 

 and contains, besides the coffin, navicular and part of the small 

 pastei'n bones, the sensitive laminae, plantar cushion and the 

 lateral cartilages. 



The sole of the foot incloses the box on the ground surface, is 

 shaped like the circumference of the foot, except that a V-shaped 

 opening is left behind for the reception of the frog, and is con- 

 caved on the lower surface. The sole is produced by the velvety 

 tissue — a thin membrane covering the plantar cushion — and 

 other soft tissues beneath the coffin bone. 



The horn of the sole differs from the horn of the wall in that ■, 

 its tubes are not straight and it scales off in pieces over the 

 entire surface. 



The frog is a triangular-shaped body, divided into two equal 

 parts by a deep fissure, extending from its apex in front to the 

 base. It fills a triangular space in the sole to which it is ulti- 

 mately attached by its borders. 



The horn of the frog is produced in the same manner as the 

 sole, but it differs from both the wall and sole in that the ho.rn is 

 soft and moist, and elastic to a remarkable degree. It is the 

 function of the frog to destroy shock and to prevent slipping. 



The sensitive laminae are thin plates of soft tissue covering 

 the entire anterior surface of the coffin bone. They are present 

 in great numbers; and, by filing into corresponding grooves on 

 the inner surface of the horn of the wall, the union of the soft 

 and horny tissues is made complete. 



The plantar cushion is a thick pad of fibrous tissue placed be- 

 hind and under the navicular and coffin bones, and resting on the 

 sole and frog. Its purpose is to receive the downward presure 

 of the column of bones and to destro\' shock. 



