22 



THE AMERICAN NATURALIST [Vol. LIII 



The relation between the percentage of hulled kernels 

 on the parent and the percentage of hulled kernels on the 

 heterozygous offspring for this series is shown by the 

 correlation table given above. The correlation coefficient 

 is. 421 + .022, which shows a very definite relation be- 

 tween the percentage of hulled in the parent and offspring. 



This relation is also better shown by means of a curve 

 (Fig. 6) in which the parents are represented by the 

 dotted line beginning with the lowest and increasing to 

 the highest value. On the same ordinate is plotted the 

 average value for the heterozygous offspring, and to this 

 line has been fitted a straight line whose equation is 

 i/ = 20.1999 + 1.9579i(;. 



Certain of these families show a decided grouping; for 

 example that represented by 20.9 per cent, shows a de- 

 cided tendency to be grouped in the lower classes, while 

 that represented by 65.1 per cent., with five exceptions, 

 shows a grouping around the higher classes. 



Eesults of Series 382— Sixty Day X Hull-less 

 From the second generation of this cross six hetero- 

 zygous plants were selected for further study. The re- 

 sults of three of these will be discussed here. These 

 plants possessed different amounts of hulled kernels, 

 which expressed in percentages were as follows, 73.3, 

 37.7, 49.3. Thus, there was one high, one low and one 

 medium plant. The offspring of these gave the follow- 

 ing results when grouped in the three classes : 



These figures agree very well with the expected 1:2:1 

 ratio. Single heads of the heterozygous plants of these 

 three families were threshed and the percentage of hulled 



