sis" according to which organisms are supposed to repeat 

 during their individual development the forms of their pro- 

 genitors (enunciated by Fritz Mueller and Haeckel). 

 Fleischmann points out the exceptions which Haeckel at- 

 tributes to "Cenogenesis," (that is to falsification) and shows 

 the disagreement among contemporary naturalists regard- 

 ing this fundamental principle. Even Haeckel's friend and 

 pupil, O. Hertwig sounds the retreat. 



The 15th chapter deals with the "Collapse of Haeckel's 

 Doctrine," which is revealed in the fact that "the practical 

 possibility of ascertaining anything regarding the primitive 

 history of the animal kingdom is completely exhausted and 

 the hope of so doing forever frustrated." "Instead of sci- 

 entists having been able from year to year to produce an 

 increasing abundance of proof for the correctness of the doc- 

 trine of Descent, the lack of proofs and the impossibility of 

 procuring evidence is to-day notorious." In the last chap- 

 ter Fleischmann finally attempts to prove on logical prin- 

 ciples the untenableness of the evolutionary idea. 



He starts from the fact that philosophers use the word 

 development to designate a definite sequence of ideas, i. e., 

 in a logical order. "Metamorphosis, says Hegel, belongs 

 to the Idea as such since its variation alone is development. 

 Rational speculation must get rid of such nebulous con- 

 cepts as the evolution of the more highly developed animal 

 organisms from the less developed, etc." 



NaturaHsts use the word in a different sense. Instead 

 of a sequence of grades of being they posit a sequence of 



128 



