62 
Research Bulletin Xo. 2 
the F 2 families taken together contained a few individuals with 
seeds smaller than the mean seed size of Tom Thumb pop and 
also a few with seeds larger than the mean seed size of Missouri 
dent. But none of the more than 300 F 2 plants had seed as small 
as the smallest of Tom Thumb pop or as large as the largest of 
Missouri dent, and neither one of the three F 2 families alone 
overlapped appreciably even the inner extremes of both parent 
varieties. F 2 family 510 with 188 plants represented in Table 24 
had a few plants with seeds nearly as small as the mean seed size 
of Tom Thumb pop but none with seeds larger than the very 
smallest seed-size class of Missouri dent. From this one F 2 
fraternity, the seven F 3 lots included in the table were grown. 
No F 3 family came from the large-seeded F 2 plants, so that very 
large-seeded F 3 lots were not to be expected. F 3 families 1139 
and 1140 were the descendants of comparatively small-seeded, 
tho not the smallest seeded, plants of 510. Their mean seed 
sizes were slightly less than the seed size of their F 2 parents and 
their smallest seeded members were quite the equal of the smallest 
seeded Tom Thumb pop plants. The rather pronounced variation 
shown by these F s families makes it seem possible that a stable 
type with seeds even smaller than those of Tom Thumb pop might 
be established by further* selection. 
