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THE AMERICAN BOTANIST, 
may impute it to the presence of certain pigmentary sub- 
stances within the cells of the leaves or the petals or the 
fruit as the case may be, this merely begs the question of 
the how and why these substances influence our eyes in 
such wonderfully different ways. We perceive color in 
fact in a somewhat topsy-turvy manner^ as we shall 
presently see. White light, as most of us know, is pro- 
duced by a combination of all the colors of the rainbow^ 
that wonderful phenomenon, indeed, resulting from the 
breaking up of the sun's rays by the prismatic raindrops 
into their various components in such a way that they 
are arranged side by side instead of being mixed up, and, 
as we know, a glass prism does the same thing. The 
difference in color in the various rays is due entirely to 
different wave lengths of the light rays, and with the 
color-producing rays are intermingled others which are 
invisible — heat rays, which are also sorted out but cannot 
be seen, but only felt. 
With these rays we have for the present nothing to 
do, so we will proceed to explain our expression of topsy- 
turvy by stating that when the rays of light fall upon 
leaves, etc., of plants, certain series of them are absorbed, 
and others rejected, and it is by virtue of those colored 
rays with which the plants, so to speak, will have nothing 
to do, that we perceive the colors we impute to them. 
Thus, to put it roughly, the green leaves absorb all the 
red rays, while the '*red, red rose" appropriates the green 
ones, and the snowy white lily rejects them all. 
How the great diversity in floral color has been 
brought about by evolution is, to a great extent, a 
mystery. Presumably primaeval flowers were green, see- 
ing that in all cases they are merely modified leaves, and 
we still see survivals of green flowers, as, for instance, in 
some of the euphorbias (our common milkweed, to wit), 
and occasionally we see reversions as in the green roses 
and dahlias. Undoubtedly, the tastes of the insect world 
have played a large part herein, since the fertilizing insects 
are certainly guided mainly by color, and in this way 
