Proenvironment in the Evolution of Man 631 



sharp edge. So the proenvironal picture took shape in the 

 improved knife of the mid- and later stone ages. But, in noting 

 that to have it all or mainly cutting edge, as not a few showed, 

 he hurt his own hand, a proenvironal picture was formed of 

 one that should be rounded or hafted below and cutting above. 

 This was incorporated into the knives of the bronze age, the 

 immense superiority of which over the best stone ones was 

 recognized. But, comparing the stone with the bronze imple- 

 ment, some inventive, aspiring, and unsatisfied mind looked 

 to securing a metal that might be even harder and keener in 

 cutting. Iron was the proenvironal reward of the proen- 

 vironal outfeeling or search. 



But, in using the knife frequently for wet operations, a pro- 

 environal picture arose of a handle that would not rust and 

 which might furnish a frictional surface. What better here 

 than the deer-horn secured in the chase, or the bone of the 

 deer's limb. Thus the bone handle was proenvironed, was 

 tried, was adopted, and is an heirloom that has come down 

 to us. 



But considerably later, as active proenvironal efforts and 

 aspirings of a manifold mechanical kind possessed man, the 

 knife joint was planned, and put into practice. Now here, 

 as in many human inventions, and in not a few animal and 

 plant variations, a distinct mutation was effected. For from 

 the rough-edged stone knife to the smooth one with elongated 

 cutting edge, from the latter to one with rounded handle, 

 and from this again to the bronze and the iron implements, 

 a steady continuous advancing variation took place. But 

 alike in the introduction of the bone handle, and still more of 

 the knife-joint for folding of the blade, a fundamentally dis- 

 tinct change and advance were made, that constituted a sal- 

 tatory or mutational variation, according to de Vries' funda- 

 mental principle. 



With new proenvironal advances, strength, neatness, and 

 varied utility were more and more secured, till the picture of 

 possible division of labor amongst several blades became the 

 aspiration that ere long was fulfilled. As a final and almost 



