MATERIALS OF EVOLUTION 51 



mon origin," — this "is the event for which we wait." 

 Bateson has worded his requirements in such a 

 way as to render the demonstration well-nigh im- 

 possible, but a somewhat different view, of the origin 

 of species through mutation may put the j)roblem in 

 another form where theoreticallv at least the diffi- 



ft 



culty is lightened even if not entirely removed. 



Suppose on Bateson's supposition that a germ- 

 cell has been produced in a male or in a female that 

 contains a single mutant gene having the required 

 property of forming a sterile hybrid. In order to 

 perpetuate itself, this germ-cell would have to meet 

 a normal germ-cell. The single individual that re- 

 sulted would by the very conditions imposed be itself 

 sterile ; for, since there are no other individuals of the 

 kind in existence there would be no means of finding 

 out that the single individual would have been fer- 

 tile with one of its kind. It would, therefore, be lost 

 because of its sterilitv. 



ft' 



The possibilities are not much better even if we 

 assimie that the mutation occia-red early in the 



ft' 



germ-track, so that several or many germ-cells came 

 to contain the mutant gene. When crossed back to 

 the parent stock several sterile individuals would 

 appear, which brings the experiment to a disastrous 

 end as before. If on the other hand two such individ- 

 uals should by chance mate then a new race miffht be 

 started which tested to the original race would be 

 found to produce offsj^ring that are sterile. Here the 



