518 BROOKLYN BOTANIC GARDEN MEMOIRS 
is obscured. As in the case of the stem colors, the different types of 
mottling appear to involve the presence and absence of several pairs 
of restriction factors. Only two of these patterns have been studied 
in detail. These are the coarse- and fine-veined types. Crosses 
between coarse and fine always give in F; all fine, indistinguishable 
from the ‘‘fine’’ pattern parent. In Fo, approximately 3 fines : 1 
coarse are obtained, the actual figures being 163 fine : 49 coarse 
(theoretical expectation 159 fine :53 coarse). Unbagged Fy. segre- 
gates having coarse mottled seed generally breed true in F3, the few 
cases where plants with fine mottled seeds have appeared being un- 
doubtedly due to foreign pollen contamination. Unbagged F». segre- 
gates with fine mottled seeds either bred true in F3 or gave both fine 
and coarse-mottled progeny. Coarse-mottled x the large splotched 
type gives a dominance of the former in F;. No F2 progeny have been 
grown. 
INTERPRETATION 
The inheritance of five of the sets of characters described in pre- 
ceding pages—green and red blush stems, red blush and mahogany 
stems, red blush and rose red stems, bloom and no-bloom, fine and 
coarse seed pattern—so far as the F,; and F» data are concerned, are 
most simply interpreted as due to the presence and absence of a single 
genetic factor in each case, making in all five genetic factors. The 
inheritance of dehiscent and indehiscent capsules is assumed to involve 
primarily two pairs of factors. No evidence of close linkage was found 
between any of these seven pairs of factors, although the data were 
taken with this end in view. 
SEED SHAPE AND DIMENSION 
Castor-bean seeds differ as to shape in being oval or orbicular 
(about as long as broad). In crosses between varieties breeding true 
to the two types, the F, plants are all oval seed, while in Fo», orbicular 
seeds are present in considerably over one fourth of the progeny sug- 
gesting a 9:7 ratio. 
Varieties of Ricinus vary remarkably in their seed dimensions 
and weight. Some of the commercial varieties have seeds less than a 
centimeter long, which run about 4,550 to a pound of 450 gm., while 
the seeds of some of the large Zanzibar ornamental types are over 2.5 
cm. long and run only 450 to a pound. Between these are numerous 
forms breeding true to almost every gradation in size and weight. 
A large number of crosses between these types have been made, 
the F, plants showing various degrees of intermediacy. All the 
