PREFACE TO THE THIRD EDITION. XXXIU 



of Biogeny, has impugned the very foundation on which 

 Anthropogeny rests. Most of his objections are, it appears 

 to me, refuted by the expLanations which I have given 

 in this third edition as to the very important relations 

 of Pahngenesis and Kenogenesis. (Compare especially 

 Chapters I., VIII., and X.) Kolliker will not recognize the 

 Gastraea Theory because he has been unable to discover a 

 gastrula in Mammals and Birds. But his experiences are 

 opposed to the most recent researches of Van Beneden and 

 Eauber, of whom the former in the case of the Piabbit, the 

 latter in the case of the Chick, describes a kenogenetic 

 gastrula-form, which, in accordance with the Gastraea 

 theory, may easily be referred to the palingenetic gastrula 

 of the Amphioxus. Kolliker says finally : "As the last and 

 most important argument, I bring forward the fact that 

 Phylogeny as read by Darwin and Haeckel does not, it 

 appears to me, represent the truth." This "most im- 

 portant argument " is a simple petitio principn. The sen- 

 tence might as well be, "phylogeny is not true because it 

 does not represent the truth." 



How very different in other respects Kolliker's concep- 

 tion of the history of evolution is from mine is most clearly 

 indicated in the " General Observations " (§ 29) at the end 

 of his book. The learned Wiirzburg anatomist there 

 exj)lains with reference to germ-history, his " essential 

 agreement in fundamental conceptions " with the un- 

 learned Leipzig anatomist Wilhelm His. I have explained 

 the nature of these " mechanical fundamental conceptions " 

 in Chapter XXIV. of this book (vol. ii. p. 352), and in 

 greater detail in my work on " The Aims and Methods of 

 the Modern History of Evolution " (" Ziele und Wege der 



