THE HORSE'S FOOT. 303 



inward inflections of the wall, which, besides strengthening it, appear to me 

 to be the calks nature has provided to prevent slipping. 



The laminae, on the inner surface of the wall, will be found a most remark- 

 able arrangement for attaching the hoof to other parts, consisting of several 

 hundred plates of horn, the "insensitive laminfe," 



The sole is that part of the foot embraced between the bars and the wall. 

 The ground surface of it is concave and generally covered with exfoliated 

 flakes, exfoliation being the procci-s by which nature removes the superflous 

 horn in this part, and not by attrition as in the case of the wall. The npper 

 surface of the sole is convex and studded in every direction with innumerable 

 minute pores for the reception of the blood-vessels from Trhicli it grjws. 

 The outer edge of the sole is dove-tailed into the ^dX\ in such a manner as to 

 make the point of union very firm. 



The frofi is the prominent triangular part occupying a chasm of the same 

 shape between the bars. It is a very important part of the foot and presents 

 for consideration a cleft, two commissures, toe, heels and two surfaces, which 

 may be referred to again. Proceeding from the heels of the frog, passing 

 upwards and around the top of the hoof, is a structure thought to be for the 

 purpose of protecting the new horn, when it grows, and called the "coron- 

 ary frog band." 



THE INTERNAL STRUCTURES OF THE FOOT. 



These are called sensitive, because they are very highly organized, possess- 

 ing an abundant supply of nerves and blood-vessels. The deep seated 

 tissues of the foot are composed of several structures which differ con- 

 siderably from one another. In the first place we have the coronary 

 substance, one of the most vascular structures of the body, situated in a 

 groove at the top of the wall, which it secretes; immediately underneath 

 the coronary substance we find the sensitive laminae, composed of say 

 500 or GOO plates formed largely of blood vessels and nerves. They, together 

 with the insensitive laminos, form the principal bond of union between the 

 hoof and the 1 /g and, being to some extent of an elastic nature, they modify 

 that concussion, the result of forcibly bringing the foot to the ground. They 

 are the seat of one of most painful diseases that horse flesh is heir to, " Lam- 

 initis or Founder." Passing around the ground border of the lamina and 

 turning the foot we come in contact with the sensitive sole, a beautiful struct- 

 ure, highly organized and composed of hundreds of little processes very deli- 

 cate and velvety looking, so much so that they are called villi^ They are the 

 terminations of blood-vessels and the point where the horn for the insen- 

 sitive sole is supplied. 



The sensitive frog is a very tough and elastic cushion situated above the- 

 horn frog. It is composed of innumerable fibers interlacing one another, 

 and embracing fat in their meshes. It is a pyramidal shaped body, having 

 its apex projecting towards the toe of the foot. The use of this organ is to 

 protect the navicular bone and tendon passing over it, as well as to modify 

 concussion to the other parts of the leg. 



The lateral cartilages are plates of gristle situated behind and above the 

 frog, intended, according to my conception, to act as springs and thus throw 

 the fatty frog into its natural position after it has been distorted by the 

 weight of the body, spreading it in various directions. They are converted 

 into bone in a disease called side-bone, which is a cause of permanent lame- 

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