140 



Plant Genetics 



PARENT) 

 RACE I SPOROPHYTE; 

 A 



PARENT) 

 RACE SPOROPHYTE; 

 B 



F,( SPOROPHYTE 



'(FERTILE) 



TILE) 



;tile) 



'(FERTILE) 



TUE) 



'(FERTILE) 



'(STBULE) 



(STERILE) 



Fig. 32.— Diagram illustrating Belling's explanation of semi- 

 sterility. 



