ORTHOGENESIS 339 



in a favourable sense, not only in a definite but also in a 

 biologically desirable manner. 



Prof. Eimer objects to Darwin setting up utility as the 

 only ruler in the organic kingdom. 



By the unconditional assumption of this supremacy it was quite 

 overlooked that utility is a purely relative conception, and that therefore 

 it cannot possibly be the fundamental principle of the forms of the 

 organic world. 



If in Darwin's assertion that every " character" occurring 

 in an organism must either be now useful "to it," or must once 

 have been useful, we substitute the word " bio-economically " 

 for "to it," Prof. Eimer's objection at once falls to the 

 ground, and we arrive at a wide standard of usefulness, with 

 the aid of which we can, as I believe I have shown to a certain 

 extent, complement Darwin's quasi-economic non-orthogenetic 

 and likewise Prof. Eimer's non-economic orthogenetic theory. 

 Prof. Eimer's method, similar to that of Prof. Keeble, 

 consists in giving himself unreservedly for once to the study 

 of a single living being, in order to penetrate into its nature 

 as deeply as possible. 



The single chosen object soon tells him more than all other animals 

 or plants together which he has observed more superficially. 



I was able to demonstrate that variation everywhere takes place in 

 quite definite directions which are few in number ; and I was able on 

 the basis of my observations to put forward the view that the causes 

 which lead to the formation of new characters in organisms, and in 

 the last result to their evolution, consist essentially in the chemico- 

 physiological interaction between the material composition of the body 

 and external influences. 



Still, such method though it has its use would seem to 

 be open to Prof. Eimer's own criticism of other methods that : 



Anything that is not teased with the needle, or cut with the micro- 

 tome or examined with the microscope is scarcely noticed at the present 

 day, except by those who are exclusively systematists even in questions 

 connected with the evolution theory. 



We have seen that chemico-physiological interaction itself 

 needs to be studied in the light of bio-economic interaction, 

 and that the explanation of " definiteness " thus becomes more 



