LOCOMOTION. 615 



The leiigth and flexibility of their bodies must also be taken 

 into account, rendering many legs necessary for support. 



The subject of locomotion is of such great importance in the 

 practice of comparative medicine that we shall now enter upon 

 it in somewhat more detail, especially as regards the horse. 

 This, of all our domestic animals, has become specialized as a 

 locomotive mechanism. All the parts of his whole economy 

 have been co-ordinated to that end ; and, except the horse be 

 viewed in this light, the significance of much in his nature 



Fio. 458.— Chillingham bull (Bos Smtieus). Shows powerful, heavy body, and the 

 small extremities adapted for land transit. Also the figure-of-8 movements made 

 by the feet and limbs in walking and running, w, t. curves made by right and 

 left anterior extremities; r, «, curves made by right and left posterior extremities. 

 The right fore and the left hind foot move together to form the waved line (*, m); 

 the left fore and the right hind foot move together to form the waved line (f, t). 

 The curves formed by the anterior (J, u) and posterior (r, s) extremities form ellipses 

 (Pettigrew;. 



will be missed. But, however well his other parts might be 

 suited to this purpose, unless the feet were adapted to rapid 

 movements and great and frequently repeated concussions, the 

 animal must soon break down. As it is, under the unnatural 

 conditions of our artificially constructed roads, faulty shoeing, 

 housing, and feeding, lamenesses of the feet constitute a large 

 proportion of the cases that fall under the care of the practitioner. 

 It may be well at the outset to give a little consideration to the 

 feet of the horse, in order to learn to what extent they are 

 adapted to natural conditions. The feet of all mammals illustrate 

 how the soft and yielding tissues are combined with the rigid, 

 to adapt to conditions of the surface over which they are re- 

 quired to move. In the carnivora, beneath the outer tough skin 

 covering the sole, there is the fatty cushion protective to the 

 bones and more delicate soft parts ; while the claws, nails, etc. 



