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119 



from the ovules of the double throwers some behaved 

 as double throwers, and some as pure singles. We 

 are led to infer, therefore, that the ovules and pollen 

 grains of the double throwers, though both produced 

 by the same plant, differ in their relation to the 

 factor (or factors) for doubleness. Doubleness is 

 apparently carried by all the pollen grains of such 

 plants, but only by some of the ovules. Though 

 the nature of doubleness in stocks is not yet clearly 



Single 



Single 



Double 



puri's4le X Ovule Pollen X ^risingle 



Single Single 



Single 



Single 



1 

 Single 



Single Double 



Single 



Double 



I 1 



Single Double 



Single 



1 



Double 



understood, the facts discovered by Miss Saunders 

 suggest strongly that the ovules and pollen grains 

 of the same plant may differ in their transmitting 

 properties, probably owing to some process of 

 segregation in the growing plant which leads to an 

 unequal distribution of some or other factors to 

 the cells w^hich give rise to the ovules as compared 

 with those from which the pollen grains eventually 

 spring. Whether this may turn out to be the true 

 account or not, the possibility must not be over- 

 looked in future work. 



