THE BONES 81 



the tibia itself. Hence in man the tibial malleolus gains the 

 ascendancy over the fibular and remains predominant. By 

 means of the two malleoli, the astragalus and os calcis are held 

 as in a vice in the same line with the tibia. 



Markedly developed in man is the os calcis (heel) for the 

 reception of the important tendon of Achilles. The arched 

 formation of the foot, which occurs only in man, causes the 

 weight of the body to be supported by the heel and the balls 

 of the great toe and small toe. The arched foot is incompatible 

 with the free movement of the great toe, possessed by the apes 

 (A. Ecker). In man the great toe together with its metatarsal 

 bone is strongly developed, the other toes being quite short. 

 In certain lower races (Veddahs, Australians), the great toe 

 forms a kind of organ of prehension similar to that of the apes, 

 but in all the higher races the power of prehension has been 

 lost ; the great toe is an organ of support, the whole foot is a 

 foot adapted for support. 



On examining the foot of an anthropoid, e.g., that of a gorilla, 

 we are struck by the essential differential characters. Here 

 the great toe diverges from the longitudinal axis of the foot at 

 an angle of 60. The opposability of the great toe is shown 

 by a furrow running lengthwise along the sole. Besides this 

 there are transverse furrows revealing still more clearly the 

 resemblance of the gorilla foot to the human hand. The other 

 toes are relatively small and slender, and are connected together 

 by a membrane which extends as far as the base of the second 

 phalanx. 1 Wiedersheim 2 has briefly summed up the character- 

 istic attributes of the human foot as compared with the anthro- 

 poid : 



(1) More complete development of the great toe ; 



(2) Reduction of the length of the toes owing to their having 

 lost the power of prehension ; 



(3) Fuller development of all the tarsal bones ; 



(4) Parallel position of the axis of the great toe with 

 respect to those of the other toes ; 



(5) Greater breadth ; 



(6) More pronounced arch formation. 



That the length of radii is absolutely, and relatively, greater 



, loc. cit., ii.. 16. 2 Wiedersheim, loc. cit., p. 95. 



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