Introductory Remarks 5 



done in a building. But there must be something 

 that makes of the work of the single genes a harmonious 

 whole, and for this purpose he assumes the existence 

 of *'supergenes."^ v. Uexkull's ideas concerning the 

 nature of a Mendelian factor and of the "super- 

 genes" are expressed in metaphorical terms and the 

 assumption of the "supergenes" begs the question. 

 The writer is under the impression that this author 

 was led to his views by the belief that the egg is entirely 

 undifferentiated. But the unfertilized egg is not homo- 

 geneous, on the contrary, it has a simple but definite 

 physicochemical structure which suffices to determine 

 the first steps in the differentiation of the organism. 

 Of course, if we suppose as do v. Uexkull and Driesch 

 that the egg has no structure, the development of 

 structure becomes a difficult problem — but this is not 

 the real situation. 



2. Claude Bernard does not mention the possibility 

 of explaining the harmony or apparent design in the 

 organism on the basis of the theory of evolution, he 

 simply considers the problem as outside of biology. 

 It was probably clear to him as it must be to everyone 

 with an adequate training in physics that natural 

 selection does not explain the origin of variation. 

 Driesch and v. Uexkull consider the Darwinian theory 

 a failure. We may admit that the theory of a forma- 



'V. Uexkull, J., Bausteine zu einer hiologischen Weltanschauung, 

 Munchen, 1913, p. 216. 



