. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 22 BULLETIN 869, U. S. DEPARTMENT OF AGRICULTURE. Jot cross. It was of intermediate density and no more variable than the parental forms. The second generation is shown in figure 1 as a multimodal curve with peaks at densities corresponding to those of the parents and the Fx generation. The homozygous forms pro- duced closely approximated the densities of the parental varieties, as is illustrated by the curves. Although there is considerable varia- bility in the means of the more lax segregates, this is no greater than
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 22 BULLETIN 869, U. S. DEPARTMENT OF AGRICULTURE. Jot cross. It was of intermediate density and no more variable than the parental forms. The second generation is shown in figure 1 as a multimodal curve with peaks at densities corresponding to those of the parents and the Fx generation. The homozygous forms pro- duced closely approximated the densities of the parental varieties, as is illustrated by the curves. Although there is considerable varia- bility in the means of the more lax segregates, this is no greater than the seasonal variation of the means of several of the 2-rowed forms. The contrast between the Pyramidatum x Jet and the JHannaX Zeocriton crosses is very striking. Each showed wide segregation so JO 40 30 X 20 I \ o 1 1 i \ 1 c '/=/ ^S\ 9. /.& /.ff ; ; ; Fig. 1.—Diagrams showing the densities of parental forms and Fi and F2 generations of a cross between the Pyramidatum and Jet barleys (upper) and of four homozygous forms from this cross in the F3 generation (lower). in the F2 generation. Hanna X Zeocriton, however, produced a much smaller proportion of homozygous forms in F3 and F4 than the Pyramidatum-Jet cross. Homozygous intermediates as well as forms with the parental densities were produced in the F3 generation. The heterozygous lines were of different types, some being as variable as the F2, while others were more variable than the pure forms, but less so than the F2 generation. The means of the heterozygous forms were also of different values. The results are illustrated in figure 2. These graphs show the parental and F2 types and four pure F3 forms of unlike densities, as well as the heterozygous lines obtained. This cross has given nearly all sorts of densities, and by this one cross the different densities of the parental forms used in these experiments have been again Please note tha
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