20 THE CASE AGAINST EVOLUTION 



back-crossed with the red-eyed wild type, whence it orig- 

 inally sprang, the product of the cross is a red-eyed hybrid, 

 which is perfectly fertile with other sepia-wild hybrids, with 

 wild flies, and with sepia mutants. This proves that the sepia- 

 eyed mutant has departed, so to speak, only a varietal, and 

 not a specific, distance away from the parent stock. Ordinary 

 or factorial mutation does not, therefore, as De Vries imag- 

 ined, produce new species. These mutants do, indeed, meet 

 the requirement of permanent transmissibility, for their dis- 

 tinctive characters cannot be obliterated by any amount of 

 crossing. Nevertheless, the factorial mutation falls short of 

 being an empirical proof of evolution, because it is a varietal, 

 and not a specific, change. In other words, factorial mutants 

 are new varieties and not new species. Only a heritable change 

 based on germinal acquisition of sufficient magnitude to pro- 

 duce gametic incompatibility between the variant and the 

 parent type would constitute direct evidence of the transmu- 

 tation of species, provided, of course, that the variant were also 

 capable of survival under the natural conditions of the wild 

 state. 



In his Toronto address of December 28, 1921, Wm. Bateson 

 announced the failure of De Vries' Mutation Theory, when he 

 said: ''But that particular and essential bit of the theory of 

 evolution, which is concerned with the origin and nature of 

 species remains utterly mysterious. We no longer feel as we 

 used to do, that the process of variation, now contempora- 

 neously occurring, is the beginning of a work which needs 

 merely the element of time for its completion; for even time 

 cannot complete that which has not yet begun. The conclusion 

 in which we were brought up that species are a product of a 

 summation of variations ignored the chief attribute of species 

 first pointed out by John Ray that the product of their crosses 

 is frequently sterile in greater or less degree. Huxley, very 

 early in the debate, pointed out this grave defect in the evi- 

 dence, but before breeding researches had been made on a 

 large scale no one felt the objection to be serious. Extended 



