4 to BOTANICAL GAZETTE [may 



which included also several other types of ratios produced by these 

 same factors. Actually the only difficult distinction which was 

 encountered was between 9:9:14 and 3:3:2, for the former (V) 

 commonly showed a deficiency of colorless grains. How per- 

 sistent and significant this deficiency is I will not venture to con- 

 clude from the limited data. Elsewhere recognition was easy so 

 long as P, R, and C were the only factors dealt with. 



Dominance 



The literature is likely to leave one with the impression that 

 dominance is complete with this set of factors. Uncertain on 

 this matter, the writer wondered whether there was any hope of 

 distinguishing genotypes from superficial appearance. In other 

 words, was a grain with the formula ppRRCC a very dark red, 

 ppRrCC or ppRRCc a lighter red, and ppRrCc a still ligher red ? 

 That such a thing might be possible was suggested by the following 

 observation. When individuals of the formula ppRRCC were 

 selfed, they regularly produced ears on which all of the grains were 

 not only red but the same intensity of red. Obviously the grains 

 were all of the same (ppRRCC) genotype. Likewise, ppRrccX 

 pprrCC would produce ears on which only 50 per cent of the grains 

 were red, but always the same intensity of red. Here, also, all 

 the red grains would be of the same (ppRrCc) genotype. In 

 contrast with this were ears so produced that the colored grains 

 represented more than one genotype. It was common in such 

 cases for quite a series of color intensities to appear. Whether these 

 different intensities to any degree represented the different geno- 

 types was an open question, but one that could be readily decided. 



An ear was chosen which had been produced by ppRrCcX 

 PpRrCc. This particular ear was noteworthy in two respects. 

 In the first place, where it should have shown a 9:9:14 ratio 

 it actually gave 57:61:57. In the second place, an unusual 

 range of color intensities appeared. Now the 9 purples theoreti- 

 cally should have been distributed among the following genotypes: 

 1 PpRRCC : 2 PpRrCC : 2 PpRRCc : 4 PpRrCc; the 9 reds, 

 1 ppRRCC : 2 ppRrCC : 2 ppRRCc : 4 ppRrCc. The writer there- 

 fore classified the grains on the basis of color intensity, with some 



