A Genetic Study of Plant Height in Phaseolus Vulgaris. 21 
a typical pole bean both in manner of growth and as regards the 
order of development of its pods. It was then transplanted to a 
large pot of rich soil and all its pods were removed. The plant 
responded promptly to this treatment by beginning growth anew. 
Both the main axis and the single side branch began again to 
elongate with gradually increasing rapidity. The side branch 
continued to grow for some time and to form pods after the manner 
of a true pole bean. The growth of the main axis, on the contrary, 
after only four new internodes had appeared, was abruptly termi- 
nated by an inflorescence exactly like the terminal inflorescence 
of bush beans. 
Several other instances of this sort have since been observed. 
These plants, however, have all been grown under normal con- 
ditions, but have all occurred in the second generation of crosses 
of several bush-bean races with a single pole-bean race. These 
bush races have not given this result when crossed with other 
pole races and the pole race, in crosses of which these anomalous 
plants have occurred, has not itself been observed to show this 
peculiarity. Such behavior is not now understood but is being 
further investigated. 
On the whole, it seems reasonable to suppose that the terminal 
inflorescence of bush beans is formed as a continuation of the 
plant axis and that it has developed thru a modification of the 
indeterminate axis of pole beans. This interpretation is supported 
both by the occasional appearance of ill-formed leaves as a tran- 
sition from the plant axis proper to the axis of the terminal in- 
florescence of bush beans and by the rare occurrence of plants 
that are typical pole beans thruout the greater part of their 
length, but whose axis terminates in a bush-beanlike inflorescence. 
The individual flower clusters of the bush-bean inflorescence are, 
then, to be regarded as the homologues of the axillary flower 
clusters or inflorescences of pole beans. In place of the leaves 
of the pole-bean axis, there occur in the terminal inflorescence of 
bush beans only small bracts suggestive of adnate stipules. 
In addition to determinate and indeterminate habits of growth, 
bush and pole beans differ in their ability to twine about supports. 
Circumnutation is strongly developed in all pole beans, but is not 
prominently exhibited ordinarily until after four or five internodes 
have developed, or until even later if the plants are growing 
slowly. Under ordinary conditions, bush beans rarely show 
prominent circumnutation, but, if forced into very vigorous 
growth, the long upper internodes develop pronounced circum- 
nutation. (See Fig. 8.) Twining habit is, therefore, not a dis- 
tinguishing characteristic of pole beans. Its absence from bush 
beans is incidental to the fact that their main axis is equivalent 
