614 



EXPERIMENT STATION RECORD. 



sun as indicated by the extent of sun spots on its surface. From tlie 

 data thus secured the author concludes that the sun sends more heat 

 to the eartli during those periods when sun spots are most numerous, 

 and that during such periods the seasons are more advanced and the 

 growth of plants more vigorous. 



The author continued during 1897 his experiments of previous years 

 on the influence of different rays of the sun on the growth of plants, 

 the principal modification of the previous experiments being the grow- 

 ing of plants of different kinds under light of varying intensity. As a 

 rule the results in these experiments with sensitive plants, strobilan 

 thus, coleus, grapes, corn, cosmos, salvia, etc., confirm those of the 

 previous experiments. In order to determine whether plants which 

 naturally grow best in a subdued light would give different results, 

 experiments were made with ferns, but these behaved in every respect 

 like the other plants experimented with. The principal results obtained 

 in these experiments are summarized in the following table: 



Growth of plants in different colored light. 



Height June 15: 



Red light 



White light ... 



Green light 



Blue light 



Height July 23: 



Red light 



White light ... 



Green light 



Blue light 



Height August 25: 



Red light 



W T hite light ... 



Green light 



Blue light 



Maximum growth : 



Red light 



White light ... 



Green light 



Blue light 



Sensi- 

 tive 

 plants. 



Cm,. 



l'.:. 

 2.5 

 2.5 

 2.5 



16.0 

 6.0 

 4.0 

 2.5 



22.0 

 8.0 

 6.0 

 2.5 



19.5 

 5.5 

 3.5 

 0.0 



Co- 

 lens ti . 



Co- 

 itus )i. 



Cm. 

 12.0 

 12.0 

 12.0 

 12.0 



40.0 

 30.0 

 18.0 

 14.0 



65.0 

 40.0 

 20.0 

 18.0 



53.0 



28.0 



8.0 



4.0 



Cm. 

 18.0 

 15.0 

 18.0 

 22.0 



50.0 

 30.0 

 18.0 

 24.0 



70.0 

 32.0 

 24.0 

 24.0 



52.0 



17.0 



6.0 



2.0 



Salvia. 



Cm. 



30. 5 



30. 

 30.5 

 30.0 



85.0 

 70.0 

 38.0 

 30.0 



150.0 

 150.0 

 60.0 

 30.0 



119.5 



129.5 



29.5 



0.0 



Cos- 

 mos. 



Cm. 

 30.0 

 30.0 

 30. 

 30.0 



80. 



70.0 

 50. 

 30.0 



150.0 

 150.0 

 60.0 

 30.0 



12.0 



12.0 



30.0 



0.0 



Spirae. 



Cm. 

 3.5 

 3.0 

 3.0 

 3.0 



20.0 



14.0 



3.0 



3.0 



50.0 

 40.0 

 12.0 

 10.0 



46.5 



37.0 



9.0 



7.0 



Strobi- 

 lan - 

 thus. 



Cab- 

 bage. 



Cm. 



12.0 

 12. o 

 14.0 

 13.0 



27.0 

 19.0 

 16.0 

 14.0 



55. 

 25.0 

 28.0 

 17.0 



43.0 



13.0 



14.0 



4.0 



Cm. 



5.0 

 5.0 

 5.0 

 5.0 



10.0 

 6.0 

 5.0 

 5.0 



5.0 

 1.0 

 0.0 

 0.0 



This table shows that as a rule the greatest growth was made in the 

 red light. 



The results of experiments with sensitive plants grown in light of 

 different degrees of intensity showed that a slightly diffused light was 

 the most favorable. With strobilauthus aud coleus intensities of G5 

 and 50 per cent, respectively, were most favorable to the growth of the 

 vegetative organs. The behavior in this respect differed widely with 

 the species of plant under trial. It is hoped by further experiments to 

 classify plants with reference to their sensitiveness to the action of 

 light, and thus to determine those plants which will be profitably bene- 

 fited by shading. For shading plants the author recommends a cloth 

 of loose texture. This not only insures the diffused light most favor- 

 able to the growth of many plants, but affords a protection against 



