Greenhouse Notes. 157 



short growth under the naked light is apparent at a glance. The 

 red field gave second poorest results in the early part of the test, but 

 it made remarkably large growths later on. At the time when 

 these readings were begun, the orange lights had the largest plants, 

 and the crop graded off through the red, blue and plain lights; but 

 about the 20th of January the differences were seen to be disap- 

 pearing. The small plants were catching up when the experiment 

 was closed, January 31st, all the fields were of nearly equal size, 

 except the naked light plants which were still weak and small. Plate 

 I showed at the right the very small plants under the naked light, as 

 compared with those in the red, next to them. In other words, the 

 l)lants in the orange field were earlier than others during the greater 

 part of their life, but they ceased to hold their own when the crop 

 approached maturity. It is impossible to say M'hy the different lights 

 should have exerted more equal effects when the plants began to 

 spread and to attain a mature condition, but such appears to be the 

 fact. Some of this equalization of growth may have been due to the 

 greater number of hours of sunlight in February, and to a slight fall- 

 ing off in the hours of electric light. While the auxanometer records 

 show wide differences at first, therefore, the general average growth of 

 the entire period is very much alike in all the examples. 



The second crop of lettuce was placed in the bed March 2d. 

 This was Grand Rapids Forcing. The light was started on the 

 8th and ran until April 25th. Essentially the same differences 

 were noticed as in the last exjjeriment, except that they were much 

 less marked, owing to the greater number of hours of sunlight and the 

 fewer hours of electric light. When the light stopped, all the fields, 

 except the naked light, were in about equal condition, 



Mevieio. — This experiment seems to show, therefore, that lights of 

 different colors exert decided iufiuences upon radish and lettuce plants 

 early in their growth; but these differences tend to disappear as the 

 plants approach maturity. The naked light, as usual, was very injuri- 

 ous to the plants; but in no other case was the infiuence of the light 

 sufficiently marked to make any important difference in the value of 

 the crop. 



Arrangements are now being made to grow plants in a spectrum 

 during the coming winter. 



