ORTHOGENESIS 299 



tion does not create new species but preserves those 

 already in existence. The main factor in the trans- 

 formation of species is a definite evolutionary direc- 

 tion which disregards usefulness completely. 



This direction is not determined by any mysterious 

 or metaphysical cause, such as Naegeli's "principle of 

 perfection." "I find," Eimer writes, "the actual 

 causes of orthogenesis to lie in the effects of external 

 influences, such as climate or nutrition, on the consti- 

 tution of a given organism." 2 



The organism, however, does not remain passive; 

 it reacts in its own and individual way; and therein 

 resides the internal cause of evolution. "Develop- 

 ment is possible only along a few lines, for the consti- 

 tution and material composition of the body neces- 

 sarily determine those lines and prevent modifications 

 from following any others." The complex of all 

 those external and internal causes acts on the indi- 

 vidual or phylogenetic growth of organisms, a process 

 which Eimer designates as organophysis or morpho- 

 physis. 



Eimer believes in the inheritance of acquired charac- 

 ters, but he disagrees with the Lamarckian view (which 

 he interprets in too narrow fashion) as the characters 

 he considers are not acquired adaptive characters, due 

 to use or disuse of organs (Cope's Kinetogenesis), 



2 On Orthogenesis and the Powerlessness of Natural Selection in Spe- 

 cies-forming, p. 22. 



