94 APES AND MONKEYS 



backs of all his fingers, from the knuckles to the nails. 

 The integument on these parts is not callous, like that of 

 the palm. The color pigment is distributed the same as on 

 other exposed parts of the body. These facts show that 

 the weight of the body is not borne on the fore limbs, as it 

 is in the case of a true quadruped, but indicate that the 

 hand is only used to balance the body while in the act of 

 walking and to shift the weight from foot to foot. The 

 weight is, therefore, not equally distributed between the 

 hands and the feet, and the animal cannot truly be said to 

 be a quadruped in habit. 



His waddling gait is caused by his short legs, stooping 

 habit, and heavy body. All animals having stout bodies and 

 short legs are predisposed to a waddling motion, which 

 is due to the wide angle between the weight and the 

 changing center of gravity. This motion is more con- 

 spicuous in bipeds than in quadrupeds, because the base 

 supporting the weight is reduced to a single point. 



The chimpanzee is neither a true quadruped nor a true 

 biped, but combines the habits of both. It appears to be a 

 transition state from the former to the latter. Vestiges of 

 this mixed habit are still to be found in man. In the act 

 of walking his arms alternate in motion with his legs. 

 This suggests the idea that he may have had, at some 

 time, a similar habit of locomotion. Such a fact does not 

 necessarily show that he was ever an ape, but it does point 

 to the belief that he has once occupied a horizon in nature 

 like that now occupied by the ape, and that having 

 emerged from it, he still retains traces of the habit. This 

 peculiarity is still more easily observed in children than in 



