1892.] The Contemporary Evolution of Man. 471 



fuse with the flexor communis: the abductors and adductors 

 of this toe are also degenerating, the latter being proportion- 

 ately large in children (Ruge). The little toe exhibits only by 

 reversion its primitive share of the flexor brevis (( Jegenbaur) ; 

 more frequently it varies in the direction of its future decline 

 by losing its flexor brevis tendon entirely. Two atavistic 

 muscles, the abductor metatarsi tpiinti 1 (always present in lb*' 

 apes), and the peroneus parvus (Bischoff), also point to the 

 former mobility of the outer side of the foot. In general the 

 bones of the foot are developing on the inner and degener- 



the hallux and of all independent movements in the little 

 toe. The associated habit is that the main axis of pressure 

 and strain now connects the heel and great toe. leaving tin- 

 outer side of the foot comparatively fiinctionlesa 



The variations in the muscular system mark off moreclearly 

 the regions of contemporary evolution, and therefore are even 

 more instructive than those in the skeleton. Muscular anom- 

 alies have, however, never been adequately analyzed. Even 

 the remarkable memoir of M. Testut, "Sur les anomalies nms- 

 culaires," is defective in not clearly distinguishing between 

 variations which look to the future, those which revert to the 

 past, and those which are fortuitous, for the author is strongly 

 inclined to refer all anomalies to reversion. 



The law of muscular evolution is specialization by the suc- 

 cessive separation of new independent contractile lauds iron. 

 the large fundamental muscles, while the law oi skeletal eq- 

 uation is reduction of primitive parts and the sp« 

 articular surfaces. The number of muscles in th< 

 a whole has, therefore, been steadily in 

 number of bones has been diminishing. In man I 

 of muscles is probably increasing in the regions of the lowei 

 arm and diminishing in every other region. The 

 rendered very difficult by the tact that some muse es {e, g 

 those connecting the shoulder with the neck and back) revert 

 to a former condition of greater- 

 employed in swinging the body by the arms, and in quaaru- 



^arwin : Descent of Man, p. 42. 



