HORSE-SIIOEIXG. 135 



posterior part is a cleft, which in the healthy state should not be deep, 

 but rather shallow and sound on its surface. 



In structure, this body is also fibrous, the fibers passing in the 

 same direction as those of the other portions of the hoof; but, 

 instead of being quite rectilinear like them, they are waw an [ 

 fiexuous in their course, and present some microscopical pecularities 

 which, though interesting to the comparative anatomist, need not 

 be alluded to here. The fibers are finer than those of the sole and 

 wall, and are composed of cells arranged in the same manner as 

 elsewhere in the hoof; they are formed by the villi which 

 thickly stud the face of the membrane covering the sensitive 

 frog. 



The substance of the horny frog is eminently elastic, and cor- 

 responds in the closest manner to the dense/ elastic, epidermic 

 pads on the soles of the feet of such animals as the camel, elephant, 

 lion, bear, dog, cat, etc., and which are evidently designed for con- 

 tact with the ground, the support and protection of °the tendona 

 that flex the foot, to facilitate the springy movements of these 

 creatures, and for the prevention of jar and injury to the limbs. 



In the horse's foot, the presence of this thick, compressible, 

 and supple mass of horn at the back of the hoof, its being in a 

 healthy, unmutilated condition, and permitted to reach the ground 

 whilfl the animal is standing or moving, are absolutely essential to 

 the well-being of that organ, more especially should speed, in 

 addition to weight-carrying, be exacted. 



The frog, like the sole, exfoliates or becomes reduced in thick- 

 ness at a certain stage of its growth ; the flakes are more cohesive 

 than those of the sole. 



It must be remarked, however, that this exfoliation of the sole 

 and frog only takes place when the more recently-formed horn 

 beneath has acquired sufficient hardness and density to sustain 



