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THE AMERICAN NATURALIST [Vol. XLVI 



purple flower PPRRCC, if the red factor is wiped out no color 

 is left. 



In an earlier paper East and Hayes 1 found four independent 

 gametic factors in maize, each of which affects the production 

 of color in the aleurone cells of maize. These four factors are a 

 basic color factor C, a reddening factor B, a purpling factor P, 

 and an inhibiting factor J which prevents the development either 

 of the red or of the purple color. Of the various points of 

 interest in the interpetation of the inheritance of these factors, 

 two have been investigated further. The first is the cause of 

 modified colors. This will be discussed at length in another 

 paper. The second is the action of the reddening factor B and 

 the purpling factor P. It was then thought that the presence 

 of the factor P together with C was all that was necessary for 

 the production of the purple color. It can now be shown that 

 the purple color develops only when the three factors P, B and 

 C are present. The production of color in the aleurone cells 

 of maize is therefore analogous to that in the flowers of the 

 genera described above, which was designated as category one. 

 This interpretation of the facts makes little difference in the 

 general behavior of these colors in inheritance and is only in- 

 teresting in so far as it unifies the interpretation of the aleurone 

 colors in maize with the sap colors of certain flowers. 



The following scheme will show the differences in behavior in 

 the two schemes. 



1. A purple crossed with a non-purple gives 3 purple : 1 non- 

 purple in F 2 . Here there is no difference in the two schemes. 

 The proper interpretation gives this result from crosses 



PPBBCC X PPBBcc or 

 PPBRCC X PPrrCC. 



2. A purple crossed with a non-purple gives 9 purple : 7 non- 

 purple in F 2 . The old interpretation was that this occurs when 

 the F x has the formula PpCc. The present interpretation is 

 that it occurs when the formula of the F 1 is PPBrCc. 



3. A purple crossed with a non-purple gives the formula 

 PpBrCc in F r If the B factor is unnecessary for the pro- 

 duction of purple, the ratio in F 2 will be (a) 36 purple : 9 red : 

 19 white. If B is necessary for the production of purple the 

 ratio in F 2 will be (6) 27 purple : 9 red : 28 white. A sample 



