424 THE AMERICAN NATURALIST [Vol. XLVI 



TIi,> studies have not vet | »r< .ceded sufficiently far to 

 justify a detailed comparison between the various forma 

 of F . hybrids and the "mutants" of De Yries. It is Hear, 

 however, that the F 2 generation will give numbers of 

 types that differ from F, hybrid plants in tin* samr 

 manner as the "mutants" differ from hamarckiana. 

 Some of the variants have characters so different from 

 the F t parent hybrid plants that they would stand in 

 taxonomic practise as new species, others have differ- 

 ences of such a nature that they might he called progres- 

 sive, or retrogressive varieties. The chances are im- 

 mensely against obtaining a LamarcManatfke hybrid 



