52 EVOLUTION AND GENETICS 



conditions are fulfilled, but the chance of recording 

 such a result at the time would be small indeed unless 

 the sterile gene itself carried with it some other 

 landmark, some new character, that would direct 

 attention to it from the beginning. Something of 

 the sort apj^ears, in fact, to have happened in a 

 stock of Drosophila studied by Plough where a new 

 race appeared whose individuals are more fertile 

 inter se than with the parent stock. 



The conditions for producing a hybrid sterile race 

 may appear more favorable in a monoecious form, 

 as in a plant with stamens and pistils in the same 

 flower. While a mutation in a single germ-cell would 

 again not improve the situation, yet if mutation 

 occurred early in the germ-track, and both pollen 

 grains and ovules came to contain the gene, self- 

 fertilization would start a race that fulfils the re- 

 quirements. These if inbred would then be found to 

 be fertile infer se and produce fertile offspring, and 

 with the parent type they would produce sterile 

 hybrids. • 



It is obvious, as I have said, that tlie chance of 

 detecting such a mutant type would be veiy small 

 unless its mutation involved some other character 

 than the one under discussion so that it could be at 

 once recorded. 



The necessity of putting the Mutation Theory 

 to the test that Bateson calls for, seems to me very 

 doubtful, for while this is one of the possible ways in 



