-A-.—Yellow Cosmos, upper portion of which was placed in the light-proof chamber on June 13 and 
received thereafter only 10 hours of light daily. The lower portion of the plant received the light of 
the full length of day. In response to the short day, flower buds were visible in the upper portion of 
the plant by June 25, and the first open blossom appeared July 9. The lower portion, exposed to the 
long day, remained vegetative throughout the summer 
B*—Sister plant of the individual shown in Plate 1, A. This plant was grown under long-day con¬ 
ditions until June 13, when it was given 10 hours of illumination daily. Flower buds could be seen 
June 28, and the first open blossom appeared July 10. Photographed July 16. This plant repre¬ 
sents the typical behavior of yellow Cosmos when exposed to a short day. The behavior of the plant 
when exposed to long days is illustrated by the upper portion of the individual shown in Plate 2, B 
