THE GAITS IN PARTICULAR. 539 



duces isochronous beats, and more or less places the hind-imprints an- 

 terior to the fore-imprints ; it is this which several authors have called 

 the ordinary walk, because it is that of all horses walking at liberty. 

 It is the same with the horse which is mounted, whose rider leaves 

 the reins hang loose. In both cases the gait is slow. 



If, however, the horse no longer has the free play of his neck ; 

 if the rider progressively raises the latter by the action of the reins, 

 being careful to increase the traction regularly, this disposition of the 

 lateral imprints will gradually diminish, then disappear at the moment 

 when they are superposed ; and, finally, their relation will be reversed 

 if the raising of the neck be continued and the horse remain unexcited. 

 The gait then takes the character of the slow, marched trot ; besides, 

 its rhythm becomes entirely different. The beats, at first equidistant, 

 follow each other in rapid succession diagonally, and finally become 

 confounded. 



If the horse whose lateral imprints are superposed be forced to ac- 

 celerate his speed by increasing his action and giving freedom to the move- 

 ments of his neck, the walk does not pass indifferently into the diagonal 

 form or the lateral form ; in other words, into the trot or the amble. 

 The subject always modifies the rhythm in the sense of his acquired or 

 natural aptitudes. Thus, the trotter acquires a walk tending rather 

 towards the slow trot, while the ambler precipitates his beats laterally 

 to pass into the amble, and the trails are modified in consequence. 



It is the relative position of the head and neck that are the essen- 

 tial but not exclusive agents in these modifications of the rhythms. In 

 addition to the muscular action, the head and neck surcharge the 

 anterior or the posterior members, and favor the particular movements 

 of such or such a biped, either by hastening the action of the one or 

 retarding that of the other. When the change of the rhythm is once 

 produced, the gait is executed with a new cadence, and the respective 

 distances of the members and the imprints of the trail remain the 

 same until a new change is produced. 



External influences over the horse may also occasion remarkable 

 modifications of the rhythm, and, consequently, determine correlative 

 variations in the trail. 



If, for example, the horse ascends an inclined plane, the centre of 

 gravity is displaced backward upon the posterior limbs and prevents 

 their advancing far under the trunk ; their imprints then remain behind 

 those of the anterior. 



A similar result is obtained if the animal is attached to a vehicle 

 heavily loaded : the intensity of the resistance diminishes the amplitude 



