OTHER THEORIES OF SPECIES-FORMING. 285 



actual facts as a basis for his theory and hypothesis building 

 is one which has not been always followed by biological 

 generalisers. It is to be regretted that the polemical and 

 personal character of much of Eimer's writing has tended 

 to make his whole work less regarded than it ought to be 

 by biologists. 



That Eimer's theory does not include in any degree the 

 assumption of an inner directive or progressive force the 

 following quotation from Eimer himself shows : "Accord- 

 ing to my investigations the chief cause of transformation 

 [of species] is that determined definitive organic growth 

 (organophysis) whose expression is a definite determined 

 development (orthogenesis), which is imposed on the 

 plasma by constant outer influences, climate, and nourish- 

 ment. . . . Apart from the fact that the Nagelian assump- 

 tion of a definite determined development is a hypothetical 

 one, not proved by facts, the zoologist can hardly accept the 

 existence of such a dominant inner factor ever pushing 

 toward advance, when he recalls the host of regressive struc- 

 tures which he has to see. This tendency to progress based 

 on the assumption of 'inner growth laws' contradicts 

 flatly the assumption of outer influences as causes of 

 change. . . . And it is my belief that it is precisely 

 these outer influences, and the physiological phenomena 

 dependent on them, which are the determining factors in 

 the phyletic development just as they are in individual 

 development." 



Among American biologists who have been believers, in 

 some degree, in Lamarckism or some other form of ortho- 

 genetic evolution, Cope is the one who has most 

 dennitel y formulated his beliefs into a complete 

 theory of the method of creating and guiding 

 variation and descent lines. Cope's theory may be called 

 one of bathmism (growth-force), kinetogenesis (direct effect 

 of use and disuse and environmental influence), and arch- 



