210 HORSE, SWINE AND POULTRY DISEASES 



A word of definition is here necessary, in order to render that 

 which follows more easily intelligible. In veterinary nomenclature 

 each two of the legs, as referred to in pairs, is denominated a biped. 

 Of the four points occupied by the feet of the animal while standing 

 at rest, forming a square, the two fore legs are known as the anterior 

 biped; the two hinder, the posterior; the two on one side, the lateral; 

 and one of either the front or hind biped with the opposite leg of the 

 hind or front biped will form the diagonal biped. 



Considering, as it is proper to do, that in a condition of health 

 each separate biped and each individual leg is required to perform an 

 equal and uniform function and to carry an even or equal portion of 

 the weight of the body, it will be readily appreciated that the result 

 of this distribution will be a regular, evenly balanced, and smooth 

 displacement of the body thus supported by the four legs, and that 

 therefore, according to the rapidity of the motion in different gaits, 

 each single leg will be required at certain successive moments to bear 

 the weight which had rested upon its congener while it was itself in 

 the air, in the act of moving ; or, again, two different legs of a biped 

 may be called upon to bear the weight of the two legs of the opposite 

 biped while also in the air in the act of moving. 



To simplify the matter by an illustration, the weight of an ani- 

 mal may be placed at 1,000 pounds, of which each leg, in a normal 

 and healthy condition, supports while at rest 250 pounds. When one 

 of the fore legs is in action, or in the air, and carrying no weight, its 

 250 pounds share of the weight will be thrown upon its congener, or 

 partner, to sustain. If the two legs of a biped are both in action and 

 raised from the ground, their congeners still resting in inaction, will 

 carry the total weight of the other two, or 500 pounds. And as the 

 succession of movements continues, and the change from one leg to 

 another or from one biped to another, as may be required by the gait, 

 proceeds, there will result a smooth, even, and equal balancing of 

 active movements, shifting the weight from one leg or one biped to 

 another, with symmetrical precision, and we shall be presented with 

 an interesting example of the play of vital mechanics in a healthy 

 organization. 



Much may be learned from the accurate study of the action of a 

 single leg. Normally, its movements will be without variation or 

 failure. When at rest it will easily sustain the weight assigned to it, 

 without showing hesitancy or betraying pain, and when it is raised 

 from the ground in order to transfer the weight to its mate, it will 

 perform the act in such a manner that when it is again placed upon 

 the ground to rest it will be with a firm tread, indicative of its ability 

 to receive again the burden to be thrown back upon it. In planting 

 it upon the ground or raising it up again for the forward movement 

 while in action, and again replanting it upon the earth, each move- 

 ment will be the same for each leg and for each biped, whether the 

 act be that of walking or trotting, or even of galloping. In short, the 

 regular play of every part of the apparatus will testify to the exist- 

 ence of that condition of orderly soundness and efficient activity elo- 

 quently suggestive of the condition of vital integrity, which is simply 



