520 BROOKLYN BOTANIC GARDEN MEMOIRS 
HETEROZYGOSIS 
F, hybrids between several of the forms produced, as in many 
maize crosses, a much larger amount of seed than either parent, the 
environment being practically the same for all. F, hybrids between 
still other forms, however, failed to show this increased productivity. 
This is also true of maize F, hybrids. 
This increased productiveness in F, should be, as in the case of 
maize and tomatoes, of great commercial value, since crossing castor- 
bean varieties, where no particularly accurate results are desirable, 
is very simple and could be done rapidly. Plants of the two types 
to be crossed could be grown separately and one lot used entirely as a 
pollenizer. A large quantity of pollen from the same spike matures 
at the same time. Hence, these spikes could be cut off when nearly 
mature and laid on paper sheets till the pollen was shed—a matter 
of a day or two. The pollen could then be collected in a powder 
gun or similar device and shot over the newly matured pistils each 
morning. The male flowers on the plants used as_ seed-bearers, 
for the most part, can be easily rubbed off without injuring the 
flower spike. The amount of selfed seed by this method would be 
very small, most of the mature seed being crossed. As ordinarily 
planted commercially, one bushel of beans running 1,500 beans to 
the pound will plant anywhere from 6 to 40 acres, depending on the 
distance apart and the number of beans planted per hill (1-3 beans). 
Some of the commercial varieties run as high as 3,000 beans or more 
per pound. Castor beans produce from 10 to 40 bushels per acre, 
depending on the variety, soil, climate and length of frostless season. 
With these facts in view, it seems unnecessary to urge the commercial 
importance of using F; generation hybrid seed produced by the method 
mentioned above. Experiments to determine which varieties crossed 
together would give the greatest yields in a given locality should be 
made in regions where the beans are grown commercially, since, as 
previously stated, there is great variation in varieties as regards this 
characteristic. This characteristic of increased productivity in F, 
progeny of certain varieties, combined with such characters as ‘“‘non- 
popping”’ and high oil content, should help toward putting castor-bean 
growing on a better commercial basis in this country. No experiments 
regarding increasing the oil content through “‘selection,’”’ so far as 
the writer knows, have been made. Varieties with seed yielding 30 to 
45 percent oil are said to be already common commercially. Experi- 
ments with, and chemical analysis of the innumerable varieties would 
possibly give us strains with a much larger oil content. 
