A Genetic Study of Plant Height in Phaseolus Vulgaris. 11 
intermediate, and 10 tall plants; and these intermediate and tall 
F3 plants produced F4 progenies that segregated into short, 
intermediate, and tall, the numbers from intermediate Fa's 
being 7:4:10 and from tall F,'s 100:42:16. Von Tschermak 
concluded that this behavior necessitated the assumption of 
several factors for the difference in height of the parents and 
suggested that the results might be further complicated by numer- 
ical inequality in the formation of gametes and zygotes. 
Emerson (1904) gave an account of crosses between various 
''pole" and ''bush" races of Phaseolus vulgaris. Of the 109 Fi 
plants reported, all were pole beans. In F2, 324 pole beans and 
118 bush beans were recorded. So far as tested, all F2 bush beans 
bred true in F,^ and later generations, some having been tested 
to F7. Of the F2 pole beans, some bred true and others produced 
both pole and bush beans, 270 pole to 75 bush. It was pointed 
out in connection with this account that pole beans commonly 
differ from bush beans in at least three respects. They are 
generally taller, tho some very small pole beans, it was noted, 
are not much taller than some of the larger bush beans. As a 
rule, pole beans twine readily about supports, while bush beans 
do not, but it was noted that bush beans show the same tendency 
when growing with unusual vigor. The one characteristic 
difference was said to be that pole beans continue growth some- 
what indefinitely, while bush beans are virtually determinate in 
growth. 
MATERIALS AND METHODS. 
The studies reported in this paper have been limited to 
races of the common bean, Phaseolus vulgaris. A few crosses 
have been made between dwarf races of the common bean and 
tall races of P. multiflorus, but, both because the climate of 
Nebraska is unsuited to the growth of the latter species and 
because crosses between the two species are more or less sterile, 
it has been impossible to grow more than the Fi generation of 
such crosses. 
^ Several years ago a large number of races of beans were ob- 
tained from reliable seedsmen. Some of the early crosses were 
made with plants grown from this commercial seed, but practically 
all of the later work, including most of that reported here, has 
been done with plants that have been grown in pedigree cultures 
and guarded against cross-pollination by insects for from one to 
four generations previous to the time the crosses were made. 
In all cases, whether the plants used in crossing were grown 
directly from commercial seed or from seed of pedigreed cultures, 
selfed seed from the parent individuals has been planted along 
