THE INDIVIDUAL 95 



structure of man, provided that man assumes the hori- 

 zontal and quadrupedal position, and rests on the tips 

 of his fingers and toes. The horse has no collar bone, 

 the union between trunk and anterior extremities being 

 wholly muscular, and the relative length of fore and 

 hind legs is such as to maintain the body in a perfectly 

 horizontal rather than an inclined attitude. He has one 

 digit instead of five and rests only on the last segment of 

 it, so that the wrist corresponds to the horse's knee, 

 the knuckle to his fetlock joint and the three phalanges of 

 the finger to his first and second pastern, and pedal bones 

 (Fig. 40). Likewise the knee of the man is the stifle of 

 the horse, the calf of his leg the gaskin of the horse, his 

 heel the horse's hock, and so on as in the foreleg. As the 

 man raises his weight well up on his toes and feels the 

 tension of the muscles of the thigh and lower leg he can 

 well understand what takes place when the horse " lifts " 

 in the starting or moving of a load or in merely pro- 

 jecting his own body forward, in locomotion. 



88. Mechanical structure. — The structure of the horse, 

 mechanically considered, consists of a trunk suspended by 

 an arch, the vertebral column, supported at each end by 

 four vertical columns, the legs, the anatomical features 

 of which have already been described in Chapter II. 

 Greater weight is borne on the forelegs because the 

 appended head and neck bring the center of gravity well 

 forward of the center of the body. The arrangement by 

 which the body is slung between the two forelegs by the 

 great pectoral muscles and the slope of shoulder and 

 pastern provide for the supporting of this weight, especially 

 during locomotion, with least concussion. The center of 

 gravity being displaced further forward when the horse is 

 in motion, still greater weight is thrown on the forelegs, 



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