44 Nebraska Agricultural Exp. Station, Research Bui. 7. 
to the mean internode length of pole beans. In general the 
period of growth-rate acceleration is finished by the time the 
fifteenth internode has developed. It is true that in some plants 
retardation in rate of growth begins somewhat earlier, but the 
retardation is so slow at first that the mean internode length is 
approximately the same whether it is calculated on the basis of 
15 internodes or of a few more or a few less internodes. Since 
the growth-curve for the period of retardation in growth is 
roughly the reverse of the curve for the period of acceleration in 
growth, the mean length of the internodes developed during the 
acceleration period is not far from that of the entire plant. Thus 
the internode length of Snowfiake, as grown in 1912, was 46 mm. 
for the first 15 internodes and 48 mm. for the entire length of the 
plants. Similarly the mean internode length of Fi of a cross of 
Snowfiake with a very tall bush bean was 86 mm. for the first 
15 internodes and 82 mm. for the entire length of the plants. 
It is believed that the plant's inherent growth tendencies are 
better shown during the period of growth acceleration than at 
any later period. The period is short and during it, therefore, 
the plants are not subjected to so wide a range of weather con- 
ditions as during their whole period of growth. Moreover, the 
practical difficulties to be overcome in measuring all the inter- 
nodes of pole beans are considerable. The upper part of such 
plants is usually badly tangled. The main axis is increasingly 
more liable to injury from the wind in its higher internodes. From 
all of these considerations it has been deemed best to include in 
the following presentation of results a consideration of on^ the 
first 15 internodes of pole beans and the first five internodes of 
bush beans. 
INHERITANCE OF INTERNODE LENGTH. 
The races of beans employed in this study were, in the main, 
the same races — in fact the identical cultures — employed in the 
study of the inheritance of number of internodes, namely, the 
pole beans July and Snowfiake and the bush beans Red Marrow 
and Triumph. The peculiarities of growth of these races have 
been considered in some detail in the preceding discussion of 
methods of calculating internode length. A note regarding the 
previous breeding of the plants used in this study should be added. 
Except for a part of the plants of Red Marrow, the pedigree of 
all plants of any one race, the records of which are presented here, 
centers in a single self-pollinated plant three generations back, 
four plants in all, one for each race. All the crosses, likewise, 
trace back to the same four plants. These four plants were from 
