10 



non-purple self-colored beans contain the three 

 dominant allelomorphs, PBM, associated with 

 the corresponding recessive allelomorphs, pbm, 

 the following forms and proportions may be 

 expected in the second generation. In each 

 64 plants belonging to the second generation 

 there should be 



27 PBM purple mottled like F lt 



9 PbM = brown mottled or yellow mottled. 

 -9 PBm = purple self-colored or black. 



9 pBM = white, exactly like the white parent. 



3 Pbm = brown or yellow self-colored. 



3 pBm = white (with the modifier but no mot- 

 tling) . 



3 pbM = white (without the modifier but with 

 mottling). 



1 pbm = white (with neither modifier nor mot- 

 tling). 



Owing to the fact that the internal com- 

 position of the white beans has no external 

 manifestation, the four white classes having 

 different allelomorphic composition are indis- 

 tinguishable from one another, thus resulting 

 in a frequently found ratio for tripoly- 

 hybrids, 27:9:9:3:16. ~U<^ 



In this interpretation of latent character! 

 are to be found explanations of several observed 

 phenomena. Tschermak, Bateson and Emer- 

 son have noted that the behavior of a given 

 character in one strain can not be used safely 

 as a criterion for predicting the behavior of 

 an apparently like character in another strain. 

 A good illustration of this is seen on com- 

 paring with these hybrids of the 'White 

 flageolet' bean, Emerson's cross between the 

 ' Ultra ' and ' Marrowfat/ the latter being like- 

 wise a white bean. The F t hybrids were 

 brown mottled, thus showing that the 'Mar- 

 rowfat' differs from the 'Navy' or 'White 

 flageolet' in having no dominant pigment- 

 changing allelomorph. The gametic formula 

 of the ' Marrowfat ' is, no doubt, pbM , and 

 in the table above, representing the F, of the 



