128 LUTHER BURBANK 



is furnished by the double varieties. I used to 

 observe that if you crossed a double and a single 

 one, you are about as likely to get a double as a 

 single. Here, again, it would appear that the 

 double condition of corolla acts as a Mendelian 

 dominant factor, and that some of the strains 

 were themselves mixed. 



All in all, then, the columbine offers most 

 interesting possibilities for the experimenter who 

 likes to test for himself the principles of hered- 

 ity. In the matter of color, there is the wid- 

 est variation, some of the familiar forms being 

 blue, others red, yellow or white. The curious 

 spurs that characterize the flower, and the fact 

 that one variety lacks them, furnish tangible 

 features that may be tested, and the single ver- 

 sus the double corolla constitutes a third feature 

 that is also susceptible to definite observation 

 and record. 



So the experimenter who will work with a 

 small number, differing as to characteristics of 

 color and spur and doubleness, has opportunity 

 for watching the interplay of hereditary forces; 

 observing the dominance of certain hereditary 

 factors, and the recessiveness of their opposing 

 factors; and finally the segregation of the dif- 

 ferent characters and their reassembling in new 

 combinations in the second generation, that will 



