Some Laws of Heredity 39 



thought that the determiners for yellow were 

 stronger than those for green, and so a plant 

 which contained both would only produce 

 yeUow peas. The modern explanation is simi- 

 lar but simpler, namely, that if a determiner 

 for yellow is present in the fertilized egg the 

 plant that grows from this will produce yellow 

 peas, but if no yellow determiner is present the 

 plant will produce green peas. In other words, 

 peas are naturally green, but may be yellow if a 

 determiner for yellow is added. The case of a 

 yeUow-seeded plant fertUizing itself would be 

 correctly represented above. In the case of a 

 yeUow-seeded plant crossed with a green-seeded 

 we would have either 



0-0=0 



Egg Sperm Fertilized 



Egg 



or 



O- ® '0 



Egg Sperm Fertilized 



Egg 



In either case the result is the same. The 

 f ertiUzed egg has in the cross a single dose of the 



