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THE AMERICAN NATURALIST [Vol. LI 



maize. Further evidence (unpublished), however, has led 

 Professor Emerson to prefer a simpler explanation for 

 this phenomenon than linkage. 



Collins and Kempton (1911) and Collins (1912) have 

 reported a genetic correlation between aleurone color and 

 endosperm texture. In this case one of the pairs of 

 aleurone factors is apparently linked with one pair of 

 endosperm factors (horny and waxy). The data indicate 

 that there is a little less than twenty-five per cent, cross- 

 ing over. 



In a later paper, Collins (1916) describes five character 

 pairs in maize that show apparent genetic correlation. 

 But since these characters exhibit "blending" inheritance 

 and have not been analyzed from any factorial stand- 

 point, it becomes impossible to use these correlations in 

 determining the group relations between the genetic fac- 

 tors concerned. Collins also notes a large number of 

 physiological correlations in this article. 



Linkage between Aleukone and Chlorophyll Factoes 

 A definite linkage has been found in maize between one 

 of the five pairs of aleurone factors {Aa, Cc, Rr, Pp, liY 

 and one pair of chlorophyll factors of which there are at 

 least seven, as the writer has determined. Manifestly 

 this is not a physiological correlation, for it is difficult to 

 conceive of an anthocyanic pigment, limited to a single 

 layer of cells in the grain, being caused by the same 

 physiological factor that produces a plastid color, like 

 chlorophyll, so widely distributed in the plant. Breed- 

 ing evidence demonstrates that the correlation is genetic, 

 as will be seen later. 



The aleurone factor concerned is the R factor, which 

 together with C and A is needed to produce any color in 

 the aleurone cells of the corn grain (Emerson, 1917). To 

 determine linkages with any of the five aleurone factors, 

 it is obviously desirable to use material that is horao-^ 



2 Reported in a paper given hi 



