430 NAVIX ox THE HORSE. 



protect blood-vessels passing out of the coffin-bone and through 

 the sensitive sole. It is well supplied with nerves, and is very 

 sensitive, quite susceptible to injury or inflammation. Corns 

 are produced by a bruise and inflammation of the sensitive 

 sole between the crust and the bars. 



What a wise provision of nature the springy suspension of 

 the horse is ! In addition to other advantaa*es, it (iives free cir- 

 culation to the blood in the sensitive sole, etc., which Avould be 

 impeded if the coffin-bone rested on the sensitive sole. 



THE SENSITIVE FROG. 



This is a thick, irregular-shaped body, occupying the space 

 bounded above by the great flexor tendon and the skin of the 

 heel, below by the horny frog, and to the sides by the carti- 

 lages which rise up from the sides and heels of the coflin-bone. 

 It is firmly attached to all the parts ; and the coronary substance 

 and sensitive sole are also attached to it, or rather are lost in it. 

 Its posterior parts, or heels, are covered with its own skin-like 

 investment. Its under surface is marked by grooves, corre- 

 sponding with the eminences of the uj^per surface of the horny 

 frog, and fleshy projections corresponding with the grooves of 

 the horny frog. Its structure is somewhat similar to that of 

 the sensitive sole, being composed of an elastic, slightly fibrous 

 structure,' a fibrous cartilaginous part, a net-work of blood- 

 vessels, and an external skin-like covering. 



The main body of the sensitive frog is made up of a yellow- 

 ish white substance, of a spongy, slightly fibrous and elastic 

 character, and which has been mistaken for a fatty pulp, and 

 called the "fatty frog." 



The fibrous, cartilaginous part covers those parts of the 

 elastic substance, just described, on which there is greatest 

 pressure, being, in some places, as much as one-fourth of ah 

 inch thick. It also sends branches through the elastic sub- 

 stance in various and irregular directions. It appears to be a 

 frame-work to support the other structures of the sensitive 



