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THE AMERICAN NATURALIST [Vol. LI 



fact that a high percentage of the awnless plants in the 

 second generation were yellow in color and consequently 

 many of them might well carry a factor which inhibits 

 awn formation. Data will later be presented to show a 

 definite linkage between the awn-inhibiting factor and the 

 factor for yellow color in the Sixty-Day. 



Series 2501al — Burt X Sixty-Day 

 A second series of hybrids between Burt and Sixty- 

 Day behaved in a manner similar to series 514al. The Fi 

 was nearly awnless in both the direct and reciprocal 

 crosses. The F2 results are shown in Table VI. 



TABLE VI 



It will be seen from Table VI that the partially-awned 

 and awnless types of Fi gave practically the same 

 behavior, each throwing about 25 per cent, of fully-awned 

 plants in F2. 



Series 2401al - Red Texas X Sixty-Day 

 A cross between Red Texas (weakly awned) and Sixty- 

 Day gave an F^ showing only 1.3 per cent, of awning. 

 The second generation of this cross has not yet been 

 grown. 



