356 Till: CLASSICAL TRADITION 



of morphology, but, on the contrary, morphology which has 

 to decide as to the possibility of descent." 1 



Hertwig, in a word, reverts to the pre-evolutionary 



/conception of homology. " We see in homology," he writes, 



7 "only the expression of regularities (Gesetzmdssigkeiten) in 



-, the organisation of the animals showing it, and we regard 



the question, how far this homology can be explained by 



. common descent and how far by other principles, as for the 



L. present an open one, requiring for its solution investigations 



/ specially directed towards its elucidation" (p. 1/9, 1906, b). 



Holding, as he does, that no definite conclusions can be 

 drawn from the facts of comparative anatomy and embryology 

 as to the probable lines of descent of the animal kingdom, 

 Hertwig accords very little value to phylogenetic speculation. 

 It is, he admits, quite probable that the archetype of a 

 class represents in a general sort of way the ancestral form, 

 but this does not, in his opinion, justify us in assuming that 

 such generalised types ever existed and gave origin to the 

 present-day forms. " It is not legitimate to picture to 

 ourselves the ancestral forms of the more highly organised 

 animals in the guise of the lower animals of the present 

 day and that is just what we do when we speak of 

 Proselachia, 1'roamphibia and Proreptilia " (p. 155, 1906, b). 

 He rejects on the same general grounds the evolutionary 

 dogma of monophylctic or almost monophyletic descent, 

 and admits with Kolliker, von Baer, Wigand, Naegcli and 

 others that evolution may quite well have started many 

 times and from many different primordial cells. 



There is indeed a great similarity between the views 

 developed by O. Hertwig and those held by the older 

 critics of Darwinism von Baer, Kolliker, Wigand, E. von 

 Hartmann and others. It is true the philosophical stand- 

 point is on the whole different, for while many of that older 

 generation were vitalists Hertwig belongs to the mechanistic 

 school. 



But both Hertwig and the older school agree in pointing 

 out tic& petitio principii involved in the assumption that the 



1 Quoted by Hertwig. See also K. Gocbel, " Die Grundprobleme 

 der heutigen Pflanxcnmorphologie," Rial. Centrbl., xxv., pp. 65-83, 



