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THE AMERICAN NATURALIST [Vol. XLVII 



that beneath the variegated grains of the same ear, and some- 

 times self-red, the red cob spot corresponding exactly with the 

 patch of red grains. Yet the wholly red ears arising from such 

 self-red seeds invariably have wholly red cobs without respect 

 to whether the parent seeds were from a red or variegated cob 

 spot. It seems possible that in some cases the change from V 

 to 8 occurs earlier in the life of the plant than in other cases. 

 In some plants the change may, it seems possible, occur soon 

 after the cob is laid down, in which case all the cells of the 

 glumes as well as of the pericarp over a considerable area will 

 be red. In other plants it appears that the change from V to S 

 occurs independently in the rudiments of several grains, but not 

 until after the glumes associated with them have been laid down. 

 But in either case, it must be remembered, the red ears produced 

 from such red seeds always have wholly red cobs as well as 

 wholly red grains and cob and pericarp colors are coupled in all 

 later generations. Evidently, whatever is responsible for the 

 change from variegation to self-color always affects both cob 

 and pericarp colors. 



This would occasion no surprise if it were known that red cob 

 color and red pericarp color are due to identical factors. But 

 I have presented, in another place, 3 evidence that cob and peri- 

 carp colors are dependent upon distinct genetic factors which 

 are either coupled or allelomorphic in inheritance. Even if it 

 should be shown that the red color of the cob is due to identically 

 the same pigment as the red color of the pericarp, it must never- 

 theless be assumed that there are distinct genetic factors that 

 influence the distribution of this pigment. The factor S c that 

 has to do with the determination of self-pattern of cob color can 

 hardly be the same as the factor S p that has to do with the same 

 pattern in the pericarp, for, if it were the same, a cross of a 

 strain having variegated cob and variegated pericarp with a 

 strain having self-red cob and colorless pericarp should produce 

 progeny self-red in both cob and pericarp, whereas such a cross 

 actually produces ears with self-red cobs and variegated peri- 

 carp. We are practically driven, therefore, to the conclusion 

 that there must be distinct factors for self-color of the cob and 

 self-color of the pericarp, S c and S p , respectively. It seems 

 reasonable then to suppose that the same is true of the variega- 

 tion pattern and that there are both V c and V p for variegated 

 cob and variegated pericarp, respectively. 

 'Ann. Ept. Nebr. Agr. Expt. Sta., 24: 59-90, 1911. 



