236 



TILE AMERICAN NATURALIST 



[Vol. LI 



stitute one factorial group in maize. It is to be expected 

 that Rr and LI should bear a definite relationship to one 

 another. This has not yet been fully determined, although 

 there are some indications of such a linkage, for aleurone 

 color and chlorophyll development appear to.be genet- 

 ically related in different manner from that noted pre- 

 viously. 



When purple seed of certain ears are planted sepa- 

 rately from the colorless ones, the former give a distinct 

 segregation of green and white seedlings, while the latter 

 give rise not only to the green and white, but also to a 

 constant proportion of yellow seedlings. The writer has 

 determined that these yellow seedlings depend upon a 

 definite genetic factor. Over two thousand seedlings have 

 now been grown and not one yellow seedling has resulted 

 from the purple grains. Discussion of this linkage will 

 also be reserved for the later paper, or until the aleurone 

 factor concerned has been identified. This may be the R 

 factor showing its theoretical relationship to the L factor. 



Summary 



1. Linkage between the R aleurone factor and the G 

 factor for chlorophyll development shows approximately 

 20 per cent, crossovers. 



2. Crossing over takes place in both male and female 

 gametogenesis of the monecious maize plant. 



3. Preliminary tests indicate that G is also linked with 

 L, a seedling, chlorophyll factor. Consequently the factor 

 pairs Rr, Gg and LI constitute one factorial group in 



To Professor E. A. Emerson, of Cornell University, 

 who so generously has shared his material for this inves- 

 tigation, the writer is deeply indebted and desires to ex- 

 press his sincere gratitude. 



LITERATURE CITED 



Castle, W. E. 



1916. Further Studies of Piehal.l Rats and Selection, ^ith Observa- 

 tions on Gametic Coupling. Part III of Carnegie Inst. Wash. 

 Pub. Xo. 241, pp. 175-180. 



