EIGHTH LECTURE. 



THE PROBLEMS, METHODS, AND SCOPE OF 

 DEVELOPMENTAL MECHANICS. 



An Introduction to the " Archiv fur Entwickelungsmechanik der 

 Organismen" 



WILHELM ROUX. 



[Translated from the German by WILLIAM MORTON WHEELER.] l 



I. The Problems of Developmental Mechanics. 



DEVELOPMENTAL mechanics or causal morphology of organ- 

 isms, to the service of which these " Archives " are devoted, is 

 the doctrine of the causes of organic forms, and hence the doc- 

 trine of the causes of the origin, maintenance, and involution 

 (Ruckbildung} of these forms. 



Internal and external form represents the most essential 

 attribute of the organism in so far as form conditions the spe- 

 cial manifestation of life, to which the genesis of this form 

 itself in turn appertains. 



The term "mechanics of development," to designate the 

 causal doctrine of this whole subject, is employed in accord- 

 ance with the principle a potiori fit denominatio, for the evohi- 

 tion of organic form comprises the main processes and implies 

 the principal problems of organic formative operations. 



1 The translation of this philosophical essay has been attended with not a few 

 difficulties. Besides the difficulties resulting from the great compactness of Pro- 

 fessor Roux's style, there are others, not the least of which are the great concise- 

 ness of meaning with which all the terms are used, and the often very delicate 

 qualifications of the leading ideas in the various paragraphs and sentences. I 

 believe that I have rendered the ideas truthfully in the main, but I fear that it 

 has been at the expense of a somewhat forced and unnatural construction in 

 many of my sentences. W. M. W. 



