Mar. 1. 1920 Effect of Length of Day on Plant Growth 563 



Average height of test plants 12 to 14 inches and that of controls 5 to 

 6 inches. 



(2a) Exposed to light from 9 a. m. to 4 p. m. Observations on 8 

 test plants and 8 controls. Planted January 8, transplanted to 8-inch 

 pots May 3, and placed in dark house May 14. First blossoms appeared 

 July 5 to 25 on test plants and October i to 25 on controls. See Plate 

 70. 



(2b) Exposed to light from 9 a. m. to 4 p. m. Obseravtions on three 

 test plants and four controls. Planted April 14, transplanted in steam- 

 sterilized soil in i2-quart iron pails and placed in dark house June 10. 

 First blossoms appeared August i to 7 on test plants and August 30 to 

 September 8 on controls. Average height of test plants 37 inches and that 

 of controls 39 inches. 



(3) Exposed to light from 6 a. m. to 6 p. m. Observations on 6 test 

 plants and 3 controls. Planted April 14 and transplanted to 12-quart 

 iron pails containing steam-sterilized soil and placed in dark house 

 June II. First blossoms appeared August 26 to September 4 on test 

 plants and September 3 to 20 on controls. Average height of test plants 

 48 inches and that of controls 49 inches. See Plates 71 and 72, A. 



(b) N. tabacum; Stewart 7o-Le;af Cuban,^ giant type: 



(i) Exposed to light from 9 a. m. to 4 p. m. Observations on 6 

 test plants and 5 controls. Planted April 14 and transplanted in steam- 

 sterilized soil in 12-quart iron pails and placed in dark house June 10. 

 First blossoms appeared August 16 to September 2 on test plants and 

 September 24 to October 10 on controls. Average height of test plants 

 53 to 69 inches and that of controls yT, to 84 inches. 



(c) N. tabacum; Connecticut Broafleaf:^ 



(i) Exposed to light from 9 a. m. to 4 p. m. Observations on 11 

 test plants and 10 controls. Planted April 14 and transplanted to 

 14-quart iron pails and placed in dark house June 5, First blossoms 

 appeared July 18 to 24 on test plants and July 17 to 22 on controls. 

 Average height of test plants 38 inches and that of controls 34 inches. 

 Average number of nodes on test plants 36 and same number on controls. 



(la) Exposed to light from 9 a. m. to 4 p. m. Observations on 8 

 test plants and 6 controls. Planted April 5 and transplanted to 14-quart 

 iron pails and placed in dark house May 28. First blossoms appeared 

 July 13 to 20 on test plants and July 7 to 15 on controls. Average height 

 of test plants 37 inches and that of controls 40 inches. 



(d) N. RUSTIC a: 



(i) Exposed to light from 9 a. m. to 4 p. m. Observations on 5 

 test plants and 3 controls. Planted April 14, transplanted to 14-quart 

 iron pails, and 5 plants placed in dark house on June 2. Test plants 

 blossomed July 5 to 28 and controls July i to 12. 



' Horticultural variety. 



