Mar. 1, 1920 Effect of Length of Day on Plant Growth 561 



were turning brown by July 18, and all were mature before August 10. 

 Average height of test plants 5 to 6 inches and that of controls 42 to 43 

 inches. Test plants were restored to normal light exposure June 20. 



(2) Exposed to light from 9 a. m. to 4 p. m. Planted May 8, up May 

 17, and placed in dark house May 20. First blossoms appeared June 

 10 on test plants and July 21 on controls. Average height of test 

 plants 8 inches and that of controls 45 to 48 inches. See Plate 65. 



(2a) Exposed to light from 9 a. m. to 4 p. m. Planted May 8, up 

 May 17, placed in dark house June 7. First blossoms June 29. Aver- 

 age height of plants 16 to 17 inches. 



(3) Exposed to light from 9 a. m. to 4 p. m. after blossoming. 

 Planted May 7, blossomed July 9, and first placed in dark house July 10. 

 By July 26 there were many full-grown pods on test plants while there 

 were none on controls more than half-grown. By August 29 the leaves 

 had yellowed and were falling, and some pods were fully ripe on test 

 plants while control plants were still green. By September 7 all seeds 

 were fully ripe on test plants, but those on controls did not fully mature 

 till about October i. See Plate 66. 



(4) Exposed to light from 6 a. m. to 6 p. m. Planted and placed in 

 dark house June 11, up June 16. First blossoms July 7 on test plants 

 and August 6 on controls. Average height of test plants 14 to 15 inches 

 and that of controls 39 to 40 inches. 



(5) Exposed to light from daylight to 10 a. m. and from 2 p. m. till 

 dark. Planted June 14, up June 19, and placed in dark house June 19. 

 First blossoms July 29 on test plants and August 1 1 on controls. Aver- 

 age height of test plants 25 to 26 inches and that of controls 41 to 42 

 inches. 



(c) ToKYO,^ late maturing: 



(i) Exposed to light from 10 a. m. to 3 p. m. Planted May 8, up May 

 17, and placed in dark house May 20. First blossoms appeared June 13 

 on test plants and July 29 on controls. Average height of test plants 

 7 to 8 inches and that of controls 49 to 50 inches. Test plants were 

 restored to normal light exposure June 20. 



(2) Exposed to light from 9 a. m. to 4 p. m. Planted May 8, up 

 May 17, and placed in dark house May 20. First blossoms appeared 

 June 13 on test plants and July 29 on controls. Average height of test 

 plants 7 to 8 inches and that of controls 49 to 50 inches. 



(2a) Exposed to light from 9 a. m. to 4 p. m. Planted May 8, up 

 May 17, and placed in dark house June 7. First blossoms appeared 

 July 4. Average height of plants 23 to 24 inches. 



(3) Exposed to light from 6 a. m. to 6 p. m. Planted and placed in 

 dark house June 1 1 , up June 16. First blossoms appeared July 14 on test 

 test plants and August 21 on controls. Average height of test plants 17 

 to 18 inches and that of controls 42 to 43 inches. 



'Horticultural variety. 



