WHITE: INHERITANCE STUDIES ON CASTOR BEANS 517 
presence of B and absence of A, the capsules would be thick and 
leathery, but non-popping. When both A and B are absent, the 
capsules would be thin, brittle, and non-popping. On this provisional 
hypothesis, “‘non-poppers”’ of the aB class crossed with those of the 
Ab class would give all AB or “‘poppers” in Fy anda 9 : 7 ratio in Fo. 
The two types used in the above-recorded crosses would be represented 
by the formulae 
AABB = “poppers,” 
aabb = “non-poppers.”’ 
Crosses of these would give a 9 : 7 F» ratio, such as that actually 
obtained. 
Seed-coat Colors 
Seed-coat colors in castor beans are white, brownish yellow, 
various shades of red, gray, brown, and black. With one exception, 
all forms, so far as the writer knows, have seed coats in which the 
ground color is modified by one of several mottling patterns, although 
the mottling patterns are inherited, as in garden beans, independently 
of the ground color. The nearest approach to a self color in the 
writer’s collection is a black-seeded variety having in some cases very 
few mottling marks and in others none at all. Efforts have been 
made to discover a self-colored white-seeded variety, but so far with 
no success. 
In crosses, chocolate brown is dominant over black. red, white 
and gray. No Fs data are available from any crosses excepting those 
of red X brownish gray and its reciprocal. The F, is brown on a 
gray background. In Fs, segregates of various degrees of redness 
appear as a minority. By counting all those Fy. segregates with a 
red cast, an approximation to a ratio of 3 brownish gray : 1 reddish 
gray is obtained. The actual results are 172 non-red : 40 reddish 
gray or red, the theoretically expected results being 159 non-reds : 53 
red gray. No reds as brilliant as the grand parental type appeared, 
showing that more than a single pair of factors is involved. 
In F3, seed from unbagged F», light red segregates gave all light 
reds in the majority of cases. Seed of the same kind from medium 
red F, segregates also bred true. Seed from unbagged brown F>2 
segregates gave browns of various shades in some cases in F3, while 
in others, browns, reds, and brown grays were produced. Reds as 
brilliant as the red ancestor were secured from red F2 segregates. 
At least three types of seed-coat color mottling can be distinguished 
definitely in castor-bean seeds. One is coarse-veined, one is fine- 
veined, dotted and splotched, while the third is characterized by a 
very few large splotches. When the seed-coat is black, the mottling 
