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ed ; a fourth cup was placed under a similar vessel 
that contained a yellow fluid ; a fifth, beneath a si- 
milar vessel filled with a red fluid ; and a sixth, un- 
der one that contained a fluid of a violet hue ; so 
that through these fluids, the yellow, red, and violet 
rays were respectively transmitted, while the others 
were, for the most part, intercepted. 
435. Observing, then, the effects produced by the 
different portions of light, which were thus permitted 
to act, he found that the plants, illuminated by the 
yellow rays, grew most rapidly in height ; next, those 
in the violet rays ; afterwards, those in the red rays. 
The plants which grew in light, transmitted through 
water, were still smaller, and approached in size to 
those which flourished in the open air ; while those 
in perfect darkness attained the greatest height of 
all. These last plants perished on the eighth day, 
and those in the yellow light on the ninth day ; 
while all the others continued to vegetate. At the 
end of about five weeks, the plants, growing under 
the red vessel, were four inches and nine lines in 
height ; under the violet vessel, three inches and 
three lines ; under the water vessel, two inches and 
ten lines ; and one inch and three lines in the open 
air. 
436. With respect to the general appearance of 
the plants, the leaves of those which grew in red 
light were smaller and less smooth, than those of 
the plants in violet light ; or than the leaves of the 
plants confined under water, or than the leaves of 
those which grew in the open air. As to colour, 
the leaves exposed to yellow light were at first green, 
