PLATE ii 
A. —Honey sorghum, grown in greenhouse and exposed to electric illumination 
from sunset till midnight during the summer and fall months. Under these con¬ 
ditions branching was confined mostly to the top of the plant. This type of branch¬ 
ing resembles that seen in Cosmos at time of flowering and represents an advance 
toward the sterile, nonbranching type of stem, as compared with basal branching 
under a shorter length of day. Photographed November 4. 
B. —Control planting or sorghum exposed to natural illumination only In this case 
there is extensive branching at the base, the new shoots developing rapidly and 
flowering freely. 
