PLATE 72 



A. — Control series of Maryland Mammoth tobacco in 12-quart buckets left out of 

 doors during the experiment . Flower heads just beginning to show when photographed 

 August 19, 1919. 



B. — Asier linariifolius L. Plants in box on left exposed to light from 9 a. m. to 

 4 p. m. daily. In full bloom when photographed June 24. Plants in box on right 

 left out of doors during the test. Showed no indications of flower heads when photo- 

 graphed June 24. 



