82 
Adams .— The Effect on Certain Plants of 
The average height on 12 July of the unshaded plants over those 
shaded was 10-3 per cent. ; on 23 July this had increased to 24*5 per cent., 
while on 30 July it was 24*9 per cent. 
Experiments in Frame , 792/. 
The first set of experiments during 1921 was made with seeds planted 
in the soil within the frame. The under surface of the windows used as 
a roof was covered with sheets of brown paper firmly secured to exclude the 
light. The check lot of plants in a frame immediately adjoining the first 
was left uncovered throughout the experimental test. 
It was found in practice that this method was less satisfactory than the 
tests carried out in the greenhouse or the open ground, as the factors other 
than light were more difficult to control. More moisture was evaporated 
on.sunny days from the soil of the uncovered frame than from the one that 
was darkened. This was remedied to some extent by watering the 
uncovered plot occasionally. The temperature inside the covered frame as 
well as the relative humidity were higher than in the adjacent frame left 
uncovered. On jo June the temperature at 3*25 p.m. was ioi° F. inside 
the frame, while it was 95 0 F. outside it. The relative humidity at the same 
time was 57 inside the frame and 51 outside. Notwithstanding these 
difficulties it seems advisable to give the results obtained, as they serve to 
corroborate the figures obtained by other methods. 
The darkening of the frame extended from the 2nd to the 25th of June 
and took place on nineteen days in all. The total duration of darkening 
amounted to eighty-five and a half hours, or an average of three hours 
thirty-four minutes for each of the twenty-four days during which the 
experiment lasted. The shortest period of darkening the frame on any one 
day was two hours, and the longest six hours, while the commonest was 
five hours. The average length of day between the 2nd and 25th of June, 
measured from sunrise to sunset, amounted to fifteen hours thirty-four 
minutes. The effect of covering the frame was to make the daily amounts 
of daylight and darkness equal during the twenty-four days of the experi¬ 
ment. The weather during fifteen of these days was bright and sunny. 
Care was taken to ensure that the frame was not covered when rain was 
falling. 
The plants experimented with were Flax, Wheat, and Soy Bean. 
Flax in Frame, 192.1. 
The seeds were sown in two rows on 23 May, one row in each frame. 
On 2 June seventy-eight plants were left in each row, and on 21 June the 
number was still further reduced, thirty-two being left in the uncovered 
frame and thirty-one in the one darkened. 
