Smithsonian Report, 1920 — Garner and Allard. 



Plate 1 3. 



1. Dahlia. Plant on right exposed to sunlight for 10 hours daily, beginning May 20. First blossom 

 opened July 8. Plant on left, which was exposed to sunlight for the whole day throughout the test, 

 did not flower till September 27. Photographed July 8. 



2. Radish. Planted May 15, 1919, and exposed to seven hours of sunlight daily till October, after 

 winch it was exposed to the sunlight for the whole day, in the greenhouse. When photographed, 

 January 5, 1920, the root was nearly 5 inches in diameter and the leaves were IS inches long. The 

 radish requires a long day to attain the flowering stage. 



