136 THE EXTERIOR OF THE HORSE. 



General Considerations relative to the Direction of 

 THE Croup. — If the reader is not already discouraged by having fol- 

 lowed us in the minute analysis which we have given, he will now 

 recognize that the terms horizontal croup and oblique croup only have 

 a relative signification, always more or less vague, unless they are 

 somewhat arbitrarily defined. He will know that such or such a croup 

 is not necessarily well directed, from the statement that the ilio-ischial 

 line is oblique or horizontal, as the case may be. He will then under- 

 stand the distinctions to be made in the two factors, the ilium and the 

 ischium, which occupy such an important relation in the modification 

 of the general direction of the coxse. Finally, he will perceive that 

 each special aptitude of the horse is associated with a particular 

 inclination of the one or the other of these factors. 



The modern horse must respond, by his conformation, to multiple 

 purposes. The two principal, which embrace all the others, require 

 the animal to employ either force or speed. The muscular forces, 

 however, which in the two cases are intrusted with the double result, 

 must, for the production of the one or the other, act according to a 

 mechanism entirely different as to its mode of construction. Whence 

 we meet certain qualifications, absolute for speed, while those for force 

 may be absent, and vice versa. 



In this region of the croup, any osseous inclination which implies 

 long gluteal and ischio-tibial muscles, a large femoral extension, and a 

 transmission of the motor impulse as horizontally as possible, should be 

 considered as the three factors which exemplify the best conditions of 

 speed. 



The distinctly-horizontal croup has an inclination of 20 to 30 

 degrees, a low ilium inclined 25 to 30 degrees, a horizontal ischium, 

 and an open ischio-ilial angle. The animal thus conformed will have, 

 if the femur be well directed, a coxo-femoral angle of 105 to 110 

 degrees. This increases the arc of oscillation of the thigh, the limit 

 of which during extension passes well beyond the vertical line of the 

 members. We know, in fact, that the impulsive force especially is 

 only utilized during progression after the moment that the direct axis 

 of the member has passed beyond the vertical line passing through the 

 centre of the coxo-femoral articulation. 



Such a horse, however, becomes incapable of carrying, Avithout great 

 fatigue, a heavy weight on his back ; light jockeys, therefore, are 

 necessary for the running-horse ; the vehicle which he draws must also 

 be very light. Constructed for running, and carrying only his own 

 weight, his speed will be extreme ; more than this should not be 



