38 Nebraska Agricultural Exp. Station, Research Bui. 7. 
all lots that it seems reasonable to conclude that the two F4 
families were breeding essentially true to distinct types with 
respect to number of internodes. It seems clearly evident from 
these results that a tendency to develop a comparatively large 
number of internodes, as bush beans go, was inherited in a bush- 
bean family from the pole-bean parent of a cross with a bush 
bean of comparatively few internodes. 
It may be concluded, then, in so far as any conclusion can be 
drawn from the somewhat unsatisfactory records here presented, 
that genetic factors concerned in the determination of number of 
internodes in bean plants are distinct from factors for habit of 
growth and are inherited independently of them, so that, with 
respect to number of internodes, it is possible, from a cross between 
a pure strain of bush beans and a pure strain of pole beans, to 
isolate types of both bush and pole beans with other internode 
numbers than those of the parent races. The bearing that this 
may have upon the possible modifications of genetic factors thru 
crossing will be discussed in a later section of this paper. 
CALCULATION OF INTERNODE LENGTH. 
Habit of growth — determinate or indeterminate — has an 
influence upon the average internode length of a plant as well as 
upon the number of internodes. It is obvious that a bush bean, 
in which growth of the main axis is terminated when the period 
of acceleration in rate of growth has barely begun, cannot have so 
great an average internode length as a pole bean, in which growth- 
rate acceleration has continued thru a long period. For instance, 
a race of the tallest bush beans that have ever come to my 
notice had a mean internode length for the first six internodes 
of the main axis of only about 37 mm. as grown in 1912, while 
the shortest pole bean with which I am acquainted, when 
grown under similar conditions, had a mean internode length 
of about 48 mm. for the first 15 internodes. The mean 
length of the first 6 internodes of these same pole-bean 
plants was, however, only about 33 mm. Obviously this 
large bush bean has an inherent tendency to produce longer inter- 
nodes than the small pole bean, but it cannot do so because its 
growth is terminated at an early stage of development. That 
such a tendency to produce long internodes is a characteristic 
of the tall bush bean is indicated by the Fi progeny of a cross 
between it and the small pole bean. The mean internode length 
of the cross was about 34 mm. for the first 6 internodes and about 
86 mm. for the first 15 internodes. The latter is 1.8 times the 
mean length of the first 15 internodes of the pole-bean parent. 
