336 



GROWTH OF PLANTS 



Figure 137. Digitalis after low temperature treatments. A and B, November 18 

 1938. A, Control held continuously in greenhouse. B, Dark room at 50 I (10 ^^ eacn 

 night, May 14 to September 30, then long days in warm greenhouse. C, January 4- ^y^lj- 

 Same dark room as B except week-ends only outside from May 10 until ^^ptember 12^ D 

 Held continuously in 41° F (5° C) dark room from May 10 to September 12 E, bame 

 as D, except returned to outside each week-end. F, Cold dark room each mght and out- 

 side each day. (D, E, F, Condition of plants at end of cold treatment.) 



