77 



original differences are comparatively of low degree, and the new auto- 

 somal genes represent in some cases small differences in somatic appear- 

 ance and in one case a large difference. The mutations in the bar gene 

 so far have been of large degree in all cases, bringing the bar stock back 

 to its original condition. 



5. The demonstration of all three of these modes of producing an 

 effective selection in the case of a single character indicates clearly that 

 the selection problem and with it the problem of stability of the unit 

 factor or gene is not capable of solution by any single formula. 



