WHITE: INHERITANCE STUDIES ON CASTOR BEANS 515 
Red blush X mahogany and reciprocal gives rose or carmine- 
stemmed plants in Fy, and approximately 1 red blush: 2 rose: 1 
mahogany in Fe, the actual figures being 47 red blush: 144 rose: 
47 mahogany, theoretically expected 59.5 red blush: 119 rose: 59.5 
mahogany. No Fs; generation of this cross has been grown, but from 
the above ratio the plants with rose-colored stems are expected to 
produce all three Fy types again, while the other two types are ex- 
pected to breed true. 
As previously stated, there are forms with rose-colored stems that 
breed true. These when crossed with red blush varieties give all 
rose-stemmed F, plants, indistinguishable from their rose-stemmed 
parent. In Fs, these produced 429 rose: 145 red blush, the the- 
oretically expected proportions being 430.5 rose: 143.5 red blush. 
Associated with the types of stem coloring are pigmented areas 
in other parts of the plant. The mahogany-red-stemmed plants have 
mahogany-red leaves and fruits. The rose- and red-blush-stemmed 
types have green leaves with red or reddish-green midribs. The dark 
purplish-red- (mahogany bloom) stemmed plants have dark purplish- 
red leaves and fruits. Plate XXIII is a much enlarged micro-photo- 
graph in natural colors showing the pattern and distribution of the 
pigmented areas in the leaf of the mahogany type. The pattern 
resembles one of the mottling patterns in castor-bean seed coats, and 
possibly may be due to the same cause. It occurs only in the forms 
with dark red or purplish-red leaves and stems, and may be regarded 
as resulting from the absence of the pattern restriction factor previ- 
ously mentioned. 
Bloom 
Bloom, similar in appearance to that on grapes, in castor beans 
consists of a scale-like waxy substance, which, under the microscope, 
resembles a piece of cracked frozen ground. It is easily rubbed off. 
This covers the whole plant and is especially noticeable on the stems 
and fruit capsules. In some varieties, it is produced more freely than 
in others. Many forms are known which breed true to its absence. 
When it occurs on plants with mahogany stems, a dark purple or 
purplish-black effect is produced (see Fig. D, Plate XXIV). 
Crosses of bloom X no-bloom give either complete or partial domi- 
nance of bloom in F;. In Fs, approximately 3 with bloom: I no- 
bloom were obtained (actual numbers being 1,108 bloom: 377 no- 
bloom, the theoretically expected being 1,113 bloom: 371 no-bloom). 
In F3, seeds from unguarded F, plants without bloom produced only 
plants without bloom. Seeds from unguarded F», plants with bloom 
either bred true in F; or gave 3 bloom: 1 no-bloom families. In one 
