312 THE EXTERIOR OF THE HORSE. 



biotes or chorioptes spathiferus. It resides in the coronary band, the fold of the 

 pastern, and the footlocli, which are soon covered by an abundant scurfy desqua- 

 mation of the epidermis and gradually deprived of their hairs. This mange is 

 benign, in consequence of its very slow spreading and the little tendency of the 

 acarus towards migration ; it passes easily from one anterior or posterior mem- 

 ber to the other, whilst it is more rarely seen to be communicated from one 

 anterior member to the corresponding posterior. However it may be, this variety 

 of mange occasions decided itching, which prevails during the night or after 

 work and induces the animal to rub and bite himself From this symptom, it 

 disturbs their rest, worries them unnecessarily, and exposes them to wounds 

 which are to be dreaded on account of their situation. It is only contagious 

 from horse to horse, and not at all from horse to man. 



CHAPTER III. 



THE FOOT. 



Definition. — The foot, in its relation to comparative anatomy, is 

 all that part of the member which is below the forearm or the leg. 



This definition, on the contrary, much more limited so far as the 

 exterior is concerned, is here applied only to the extremity of the 

 members which rests upon the ground, the nail, properly so called, the 

 horny box, vulgarly known under the name of the hoof, which contains 

 and protects living, sensitive tissues of variable texture and properties. 



Distinction. — Four in number, the feet are qualified fore or 

 hind, according to their relative situation with the centre of gravity. 

 All have the same general organization ; they diifer, nevertheless, in 

 several external characters which we will soon explain. 



In each biped, anterior or posterior, they are distinguished as right 

 and left ; their conformation otherwise is absolutely identical. 



A. — Organization of the Foot. 



The foot has always been considered as one of the most important 

 regions to study. This will be the better appreciated when we learn 

 the part it plays in station and in locomotion, the influence of its 

 beauties and defects upon the aptitude of the animal for diverse 

 services, and, finally, the gravity of its diseases. 



More than twenty-two centuries ago, Xenophon said that the mem- 

 bers are the very first parts to be examined in the horse : " A house 

 cannot serve any purpose, however perfect it may be in its superior 



