48 R. A. EMERSON 
Intercrosses of F. color types 
It has been shown in the preceding pages that all the six color types 
occurring in F, of a cross between purple and green behave in Fs and later 
generations as is expected on the basis of the three-factor hypothesis 
suggested to account for the F2 results. It remains to determine whether 
the several color types behave in accordance with the hypothesis when 
intercrossed one with another. Of the fifteen possible intercrosses between 
phenotypically different types, two have already been discussed. The 
cross of purple with green has formed the basis of the whole discussion. 
The cross of dilute sun red with brown, since it was expected to give the 
same results as the original cross of purple with green, was most conven- 
iently considered with that cross in generations later than Fy. The results 
of this second cross have been in accord with expectation. The other 
thirteen intercrosses are now to be considered, together with intercrosses 
of some types that are phenotypically alike. 
Dilute sun red IVa x green VIa, VIb, VIc.— The progenies of self- 
pollinated green plants were listed in table 15 in several groups in 
accordance with what was learned of their genotypic constitution by the 
crosses to be considered here. The regular Fs lots, from self-pollinated 
F, greens of self-pollinated F, purples, were put in group 1 of table 15. 
Only one of the same F» greens (table 16, group 2) was crossed with homo- 
zygous dilute sun red, A Abbplpl. The result was 67 dilute purple 
plants. Another green plant, an F; from a self-pollinated F. green, gave, 
when similarly crossed, 9 dilute purple plants (group 2). Evidently both 
these green plants were aabb Pl Pl. Four other F; green plants, when 
crossed with dilute sun red, gave a total of 148 sun red plants (group 1, 
table 16). One of these four belonged to an F; lot containing browns and 
greens in a 3:1 relation, and could not, theoretically, have done other 
than give all sun red or all dilute purple when crossed with dilute sun red. 
Two of the four were from greens of an F'; lot made up of purples, sun reds, 
browns, and greens, and were therefore assumed to be aaB B pl pl, 
as the crosses with dilute sun red showed them to be. One of the four 
green plants, however, belonged to an F3; lot of browns and greens in a 
9:7 relation and was consequently comparable to an F», green. A sixth 
F; green also belonged to a 9:7 lot, comparable to an F. lot. When crossed 
with dilute sun red (group 3, table 16), it gave 24 dilute sun red plants, 
