198 THe OTTAWA NATURALIST. [January 
It is true that the autumn colors, with all their beauty, are 
those of death and decay. They are in fact the swan song of the 
leaves. But this death and decay are not due to frost. The 
leaves know that their hour has come without any such reminder, 
and of their own accord, as it were, they prepare in truly cova 
fashion to leave the stage. 
In this preparation there is a general brewing up of the 
elements which compose the foliage, and this is what causes the 
change of color. Yellow, the commonest of the autumn colors, 
is produced by the decomposition of the summer’s green. The 
chlorophyll, which imparts this green color to all plants, is made 
up of two substances, one bluish and the other yellow, and in 
autumn when the leaf is getting ready to die, these two substances 
are separated. The blue disappears and the yellow remains to 
give its color to the foliage. 
The origin of the red color is not so well understood, but it is 
believed to be preduced by the waste mineral matter which col- 
lects in the tree during the summer. This is taken up by the 
roots in the water which it is their business to suppty to the tree, 
and is stored chiefly in the leaves, where it is very much in the 
way, but partly through the whoie tree. Now before the leaves 
fall the tree takes from them everything it wants to keep and gives 
to them everything it wants to get rid of, and the collection of all 
this waste matter in the leaves has much to do with their coloring. 
For this reason the color is most beautiful after a rainy summer, 
provided the fall is of the right kind. In rainy seasons there is 
more water for the roots to take up, and the more water taken 
into the tree, the more waste matter is stored up to color the 
leaves in fall. 
The only color that the frost has anything to do with is dark 
brown, When the delicate cells of the leaves are frozen they die 
and turn brown. 
With the fall of the leaf the frost has equally little to do. 
Trees shed their leaves in countries where it never freezes, and in 
the North a great many fall before the frost comes. Neither is it 
the autumn winds that make them fall, though both they and the. 
frost help a little. A wind strong enough to blow the leaves off 
would take the twigs too and very likely uproot the tree. 
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