350 



Journal of Agricultural Research voi. xxn. no. ? 



been prepared to show these differences. Two sets of frequencies are 

 represented. One set represents the classes of spelt inheritance of the 

 Fj plants of series 13255a and 13260a, which produced nothing but 

 spelt in the F3 generation. The other set shows the plants of the same 

 generation and series which proved to be heterozygous for the spelt 

 character and produced spelts as well as wheats in ratios approximating 

 3 to I. These figures are taken from the data in Tables IX and X. 



Table VIII. — Comparison of classes of spelt inheritance of tested homozygous and 

 heterozygous plants of the F^ generation 



From Table VIII it is seen that the plants which proved to be homozy- 

 gous for the spelt character occur from class i to class 4, the average of 

 their means being 1.98. The Fj plants which proved to be heterozygous, 

 on the other hand, came from practically all classes, the average of the 

 mean classes being 4.16. 



Table VIII shows that, although there is no sharp difference in the 

 phenotypic appearances of the homozygous and heterozygous individuals, 

 yet as a rule the Fj spelts of the speltoid classes (classes 5 to 9) are far 

 more likely to be heterozygous for the spelt character than those of the 

 true spelt classes (classes i to 4). 



The comparison of the distributions of the F3 populations of the Fj 

 homozygous spelts of the 3 to i and 15 to i segregating families is of 

 special interest, as, among other things, it supports the two-spelt-factor 

 explanations already given. The distributions of the F3 populations of 

 constant spelt-producing Fj individuals of each of the three series 13126a, 

 13255a, and 13260a are recorded in Tables V, IX, and X, respectively, 

 and are represented graphically in figure 3. 



