THE CHEMISTRY OF GROWTH. 93 
relieve human suffering, or to heal bodily diseases, 
are also made here. Colours bright as the rain- 
bow, and more pure in their tint than any that 
human art can compose, are likewise formed and 
locked up here, whence they are often extracted 
by man, to apply them to his own purposes. 
They are, in fact, both the receptacles and also 
the producers of every vegetable product, however 
varied in its character, or strange in its properties. 
As we proceed in our history of the life of a tree, 
this fact should never be lost sight of,—that all 
the changes and decompositions of which we shall 
have to speak, take place in these little cells, each 
of which, although independent of the others, 
because there is no opening from one into an- 
other, yet acts in beautiful harmony with the 
rest. 
We have now to ask the reader’s attention 
to the answer which Chemistry gives when she 
is asked, How does the seed come to life, and 
grow into a great tree? First we may ask, What 
are the components of the seed itself? When 
the infinite variety of seeds is remembered, and 
when we consider to what millions of different 
plants they give rise, many of which are as op- 
