Driesch 243 



tainly do not denote any endeavor of the idioplasmic 

 substance to proceed by the shortest route to the condi- 

 tion of its equilibrium. They indicate that it is quite 

 impossible on the one hand to accept the passage of 

 ontogenetic through phylogenetic forms and on the other 

 hand to refuse to this process the significance of an actual 

 repetition of phylogeny by ontogeny. In other words 

 one must seek the cause of this repetition not merely in 

 biologic laws of maintenance of the equilibrium in an 

 existing homogeneous idioplasm, but chiefly in the entire 

 past of the species and just in the historic fact that it 

 passed during its development through such and such 

 phylogenetic forms. 



And so the objection urged by Weismann against 

 Nageli can be urged in its full force and even more justly 

 against Hertwig. For though Nageli gave no explana- 

 tion of their causes and ways of action, he nevertheless 

 accepted the activation of a whole series of different 

 anlagen of the idioplasm in exactly the same serial order 

 as in their phylogenetic appearance. Hertwig on the con- 

 trary after he had first accepted this activation of succes- 

 sive anlagen of the idioplasm finally rejected it. 



Driesch 



This author's conception of organic development 

 cannot in its very nature afford any explanation whatever 

 of the inheritance of acquired characters and conse- 

 quently, admitting that this inheritance exists, ought for 

 this very reason to be considered inadmissible. It can be 

 summed up in the following words of its author. 



''Each cell concerned in the ontogenesis in so far as it 

 possesses a nucleus really carries within it the sum total 

 of all anlagen ; in so far however as it possesses a specific 



