53-2 



THE EVOLUTION OF THE HUMAN FOOT. 



thus found that the weakest transverse arch is that of the orang-, Avho 

 never walks. In man, too, the minimum is represented, as before, by 

 the men of the inferior races, the Australians and the negritos, the 

 averag-e by negroes and the maximum by Europeans (see fig, 10). 



For the longitudinal arch, whose value was obtained by measuring 

 the distance from the summit to the base of the arch, the foot being 

 placed tiat on the ground. ]M. Volkov arrived at the same results; at 

 the bottom of the scale are the Veddahs. the neg-ritos and the negroes, 

 and at the top the Europeans; the foot of the European having the 

 maximum of convexity. 



M. Volkov has also studied the evolution of this arch, in^^estigating* 

 how the flat foot of the tree dweller became such a structure as M. 



Casse has described, and the morpho- 

 logical changes of its constituent parts 

 that have ensued because of the devel- 

 opment of the convexit}". 



One of the principal consequences of 

 the formation of the arch has been the 

 inclination of the heel to the ground, 

 which we have airead}' studied, and 

 which, as would })e supposed, varies 

 directly as the degree of convexity, '' 

 this modification also occasioning a dis- 

 placement of the insertion of the Achilles 

 tendon. 



The dilierences in the position and 

 size of the lesser process of the calca- 

 neum in man and anthropoids also vary 

 according to the formation of the arch; 

 support. M, point of iaternai support. j(^g getting, for example, and the restric- 



M', point of external support. CX, . c •, t • rnu i 



anatomical axis. A. position of the tion of its duiiensions. the moukey, 



astragalus. f qj^. instance, whose foot is flattened and 



normally turned inward, has, indeed, a long and solid lesser process 



that sustains the astragalus; besides, by reason of the flattening of the 



« It follows from the indination of the calcaneuni that the length of the heel in 

 projection diminishes as the arch increases; this well-established fact explains the 

 apparent contradiction between these results and the opinion generally expressed 

 that the negroes have a longer heel than Europeans. As M. Volkov has shown, the 

 men of the so-called inferior races have in reality, anatomically speaking, the cal- 

 caneum as a whole (and the heel itself) about eqiial to that of the Europeans when 

 that bone is measured by itself and detached from its neighbors, but physiologically, 

 since, as every one knows, we ought always in mechanics to measure the arm of the 

 lever, it is longer in projection, which explains, as may l)e added parenthetically, 

 the reason why the gastrocnemius muscle is longer and slenderer in the negro, 

 shorter and thicker in the European. The well-known theory of M. Marey on this 

 subject is completely confirmed by the figures of ]M. Volkov. 



Fig. 11. — Diagram. 



X 



(', point of posterior 



