WHITE: INHERITANCE STUDIES ON CASTOR BEANS 519 
different F, plants of each were practically uniform as to seed size 
(see Plates XXV, XXVI, and XXVII). 
Most of the large-seeded forms and some of the very small-seeded 
forms (with indeterminate growth period) require a long season to 
produce mature seeds, so that even when Fy» populations were started 
in the greenhouse in pots several months before planting out, only 
about two thirds of the segregates matured seed. One year, attempts 
to overcome this difficulty by growing the plants in 10 cm. pots for a 
year were unsuccessful. The difference in seed maturity between the 
outdoor and these pot-grown plants was very slight. Because of these 
difficulties, several of the F2 populations shown in Plate X XVII repre- 
sent only part of the segregates—the small- and intermediate-seeded 
classes. In F: populations from small X large seed or the reciprocal, 
small-seeded types similar to the small-seeded grandparent and even 
smaller were obtained in every case, while in some of the crosses 
involving nearly complete F.2 populations (Plates XXV, XXVI), the 
large-seeded type was also obtained. In all crosses, as expected from 
studies of size characters in maize, poultry, and other plants and 
animals, numerous intermediates were present, so that a complete F2 
population represented a gradating series ranging from those similar 
to or smaller than the small-seeded parent to those similar to the 
parent with large seeds. 
Seeds from unbagged F2 small-seeded and large-seeded segregates 
have given similar F3 progeny, showing the extremes to breed true. 
Various F, intermediates have also bred true in F3, while other inter- 
mediates have given the whole Fy, series again. Still others have 
shown very much less variation. 
OTHER CHARACTERS 
Numerous characters, other than those described in preceding 
pages, have been studied from the standpoint of heredity, but not in 
sufficient detail, to admit of interpretation. Crosses between low- 
growing (dwarfs), early seed-maturing types with determinate growth, 
and tall, late-maturing types with indeterminate growth gave inter- 
mediates in F,, which in F, gave all three types, though accurate 
classification so far has been impracticable. Crinkled, much notched 
leaved types crossed with ordinary leaved types gave either dominance 
of the ordinary type or intermediates in F;. Some types have a loose, 
few-seeded fruiting spike, while others have a dense compact spike 
with a larger number of pods. Crosses between them give either 
intermediates or dominance of the loose spike. In F2, both types 
reappear, together with many intermediates. 
