PLATE 6 
A. —Scarlet Runner bean (Phaseolus multiflorus). The plants in this series were 
exposed to the full length of day during the summer and on October 15 were trans¬ 
ferred to the greenhouse where they received electric illumination from sunset till 
midnight, in addition to the natural daylight. Under these conditions there was no 
tuberization of stem or roots. Photographed January 18. 
B. —Scarlet Runner bean plants which were exposed to a io-hour day till October 
15, when they were transferred to the greenhouse and allowed to receive the full 
natural daylight period of late fall and early winter. Under these short-day conditions 
there was marked tuberization of the roots while the growth of vines was considerably 
less than under the long-day conditions. Photographed January 18. 
