JAN. 4, 1921 kempton: linkage in maize 15 



Through the courtesy of Prof. R. A. Emerson we were sup- 

 plied with a sample of his liguleless leaf variation (Emerson 191 2). 

 This variation is one in which the line of demarcation between 

 the sheath and the blade is lost and the leaves possess neither 

 ligules nor auricles. In the strain supplied us the color of the 

 pericarp and cob was red. This liguleless leaf variation was 

 crossed with a strain of brachytic culms which had a white peri- 

 carp and cob. 



The plants of the first generation were all normal in stature 

 with red cobs, and pericarps and the leaves all had the normal 

 ligules. Nine of these first generation plants were self -pol- 

 linated and separate progenies were grown from each of the 

 resulting ears. 



With respect to the pericarp and cob colors only two classes 

 of plants were obtained in the second generation, namely, those 

 with a red cob and pericarp and those with a white cob and 

 pericarp. This is in accord with the results of Emerson, 19 11. 



The other two characters involved (brachytic culms and 

 liguleless leaves) occurred in all possible combinations with each 

 other and with the cob and pericarp colors. Since the color of 

 the cob and that of the pericarp were always alike on any given 

 plant, it has been found convenient to refer to this character 

 simply as the color of the cob. 



The distribution of the plants of the nine progenies for color 

 of the cob and character of the culm is shown in table i . 



In each case the red cob color is found to be associated with 

 normal stature which is the parental combination. Although 

 the degree of association varies, the coefficient of association of 

 0.463 =t 0.038 for the entire group indicates a crossing-over 

 percentage of 35.5. 



Practically the same percentage of "crossovers" was obtained 

 from a cross between a Maryland red dent variety of normal 

 stature with the white-cobbed strain of the brachvtic variation. 

 The first generation plants of this cross, as in the liguleless- 

 brachytic cross, were all normal in stature with red cobs and 

 pericarps. 



