PLATE 120 
Medicago falcata sown in greenhouse January 20. Photographed March 3, 1921.. 
A. —Grown under normal day with added illumination from a 100-watt electric 
light from dusk until n p. m. 
B. —Grown under normal day. 
C. —Exposed to daylight from 9 a. m. to 4 p. m. 
