196 ANTHOCYANINS AND GENETICS 



If the modification should occur much later, for instance when the ear 

 is beginning to form, there might be then only a patch of red grains 

 on a variegated ear, and only those gametes arising from these red 

 masses of tissues would carry half S and half V. Finally if the modifi- 

 cation should occur after the grains begin to form, the latter would 

 have broad or narrow stripes according to the amount of pericarp 

 directly descended from the modified cell, and the larger the amount 

 of modified tissue the greater the chance that the gametes concerned 

 would carry S. Similarly in any cell of a heterozygous, variegated- 

 eared plant, V -- , he assumes that the V factor may be changed to S. 

 The effect on the pericarp colour would be the same as before, and of 

 the gametes arising from the modified tissue one-half, and never more, 

 would carry S, the other half would carry no factor, and would be 

 represented by . 



Emerson then applies his hypothesis to results obtained in the F 2 

 and F 3 generations. As stated above Fj red-eared plants which had 

 arisen from selfed homozygous variegated ears gave in F 2 only red-eared 

 and variegated-eared offspring. On the hypothesis quoted, the con- 

 stitution of the Fj red-eared plants would be either VS or SS, the former 

 being more frequent than the latter on account of the rarity of S in the 

 cJ gametes. The Fj red ears tested were evidently of the composition 

 VS. Of two F 2 reds from selfed F^s, one gave reds and variegated, 

 the other bred true to red. Hence the hypothesis is in accordance with 

 the results. Again F x red-eared plants which had arisen from hetero- 

 zygous variegated selfed plants, as we have seen, behaved in some cases 

 like hybrids of red and variegated races, in other cases like hybrids 

 of red and white races. On the hypothesis that variegated-eared plants 

 were V - and their red grains S , the Fj plants would be SV, SS, 

 S - , V , or - - . Of the F x reds tested some were evidently SV, 

 and others S . Of the F 2 reds, one bred true in F 3 , and others segre- 

 gated into reds and variegated. 



Finally when Fj red-eared plants arose from either homo- or hetero- 

 zygous variegated ears that had been crossed with whites they gave 

 only red-eared and white-eared offspring, never variegated. By hypo- 

 thesis the parent variegated-eared plants were V - - and VV, and the 

 red grains S - and S V (or SS possibly) and the male parents were 



- . The F x plants therefore would be S , V - and - -, and only 

 S - would be red-eared. The red-eared F x plants tested gave red- 

 and white-eared in Mendelian ratios. Of the F 2 red-eared, one bred true 

 in F 3 , and the others segregated into reds and whites. 



