124 



PHOTOCONTROL OF GROWTH 



Fig. 8. Lettuce, var. Wonder van Voorburg. Treated with GA: 0, 0.1, 

 and 1 ^g on the first day; 0.1 c and 1 c = ^g daily. Irradiation during 

 16-hr day with monochromatic light of high intensity. Photographed on 

 March 16, 1957, after 30 days of treatment. 



