No. 596] SHORTER ARTICLES AND DU 



of the pollen mother cells Frost states 

 looked for indications si i festive of de< 



that the appearance of the pollen in eve 

 breeding singles is that it is all consisted 



to dcgnier.-ilion in the -rains must needs ; 

 of them are consistently bad. In the abse 

 evidence in support of elimination of facte: 

 Hon of the pollen grains themselves Frost 



of elimination at a later point, though the 

 genealogical tree of one daughter cell in e 

 divisions of the pollen grain leading to the 

 sperms affords precisely the kind of evide 

 search. There remains the alternative v : 

 forward, viz., that both single-carrying an' 

 len is produced, but the single-carrying 

 fertilization. In order to get over the d : 

 germs of the true-breeding single are unc 

 ing but are yet able to effect fertilization 

 make one of the following alternative 

 come to the main point in his scheme 



