294 THE BIOCOSMOS PARTICULARIZED. 



Various reasons of utility may be assigned 

 for the change, but the chief ground is the 

 greater freedom, toward which the Animal 

 and indeed all Nature are ever evolving, by 

 increase in self -controlling and therewith in 

 other-controlling. A second differentiation 

 of the Extremities is into fingers and toes, 

 and in case of the hand specially the third is 

 seen in the thumb and digits, which distinc- 

 tion is slightly indicated also in the foot. 



In general the principle of separation and 

 differentiation characterizes the Extremities 

 which have separated from the Trunk and 

 have become external to it, though still 

 attached to it. So they in accord with their 

 principle keep on separating till the two arms 

 unfold into a difference of their own as right 

 and left. Herein we may see that the Plant 

 with root and branch is not only homologous 

 but remotely kindred, possibly ancestral. 

 Thus the Upper Extremities carry differentia- 

 tion considerably further than the Lower, and 

 are much more versatile in their activity, not 

 having to carry the organism (like the legs), 

 but to mediate it in great detail with the outer 

 world, being relieved of the heavy, burden- 

 bearing work. The arm (especially the right 

 one), is a skilled, light-moving workman, 

 while the leg is a muscular, strong, but plod- 

 ding day-laborer. 



