GUARDS AGAINST CONCUSSION. 6 



thnishy, the frog becomes separated, as it were, in the middle. Ion 

 gitudinally, and a deep crevice is found. The back pai't of the foot 

 is foiyiied thus : 



And it is evident that as the weight is throwoi on the heel the quar- 

 ters expand and the frog rests on the ground. The corrugated shape 

 permits this, and when the weight is removed the elastic media 

 brings it back to the original position. The ilhistration re})resents a 

 section of the foot about an inch in front of where the wall and bars 

 form an acute angle. The bar forms a curve sweeping from the 

 point of the frog to the junction above alluded to, and the fissure 

 between it and the frog is the deepest at the point which the cut 

 delineates. The wall is much stronger at the heel than what is 

 termed the quarters, and only slightly thinner than at the toe. This 

 is necessary to withstand the concussion, which is the gi'eatest at the 

 heel, and the thinner quarters admit of ♦more freedom of motion. 

 The expansion is not confined to the gi-ound surface — the whole foot, 

 from the coronary ligament to the bottom, expands and contracts as 

 the weight is thrown upon the limb, and taken from it when the 

 animal raises his foot to thi'ust it forward. In the unshod, natural 

 foot, there is nothing to prevent this freedom of motion ; it is un- 

 fettered, and performs its functions without hindrance. In the 

 gallop and the fast trot the body is hurled through the air, thei'e 

 being a time when all the feet are off the ground. The eye detects 

 this quite readily when the horse is running, but it is extremely 

 difficult to discern it in the trot. In the gallop the feet touch the 

 ground in regular succession, followed by a bound, and the ear is 

 cognizant of the fact, if the eye fails to be convinced. The sound of 



