MOVEMENTS UPON PLACE. 



471 



order to free the hind-quarters and facilitate their movement of rota- 

 tion upon tlie fore-quarters. 



Second Period. — By the sudden impulsion from the posterior 

 members and the contraction of the dorso-lumbar muscles, the eleva- 

 tion of the croup now takes place, which is a movement in some 



Fig. 170.— Kicking. 



manner complemental to the previous lowering of the head and the 

 neck. The extension of the thigh, of the leg, and of the canon fol- 

 lows almost immediately, and determines a vigorous retropulsion of 

 the hind-feet, from the sudden and simultaneous contraction of the 

 gluteal, the anterior femoral, and the gastrocnemius muscles. 



The details into which we have entered when speaking of the role 

 of the cord of the hock (see page 258) sufficiently explain the power 

 of the hind-limbs, comparable, in this respect, to an elastic spring 

 which recoils in an almost instantaneous manner, in consequence of the 

 synergetic and sudden co-operation of the agents charged with the ac- 

 complishment of this action. 



The kick has only a very short duration ; the posterior members 

 return to the ground almost immediately. Certain horses can repeat 

 it frequently and without great fatigue, like the ass ; they are short, 

 wide, and powerfid in the back and the loins, long in the croup, the 



