starting point). (lo). The law of the cessation of develop- 

 ment (a protracted cessation of development frequently 

 ensues in one or the other stage). 



The origin (perhaps rather the distinction) of species 

 is accounted for principally by the last named law, by means 

 of which Eimer also explains the so-called atavism or re- 

 version. To this law are joined other factors, e. g., devel- 

 opment proceeding in leaps, as demonstrated by Koelliker 

 and Heer; local separation (through migration; prevention 

 oi fertilization, e. g., the impossibility of cross-fertilization 

 between certain individual organisms (which Romanes had 

 already opposed to natural selection), and crossing. 



The second mam division of the book is taken up with 

 a very searching and detailed criticism of Weismann. This 

 criticism seems to me entirely warranted; because not only 

 the latter's unintelligible position with regard to natural 

 selection (the repudiation of which he seems to regard as 

 synonymous "with cessation of all investigation into the 

 causal nexus of phenomena in the domain of life") but like- 

 wise his fanciful theory of heredity, utterly devoid as it is 

 of any support from actual observation, bespeak an utter 

 lack of qualities essential to a naturalist; and the manner 

 in which he ignores his former pupil and his labors, be- 

 cause they proved embarrassing to him, is entirely unwor- 

 thy of a man of science. 



Eimer devotes special attention to "mimicry"; and in- 

 deed he was forced to be very solicitous to dispel this fan- 

 ciful conception of Darwinism which radically contradicted 



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