124 LIFE OF A TREE. 
tone more deep and full than all; and her skies, 
like those of the old masters’, abound in a pecu- 
liar richness of colour, the mere contemplation of 
which sheds a soft and almost hallowed influence 
on the mind. 
It is not, however, yet positively known what 
the difference in light here spoken of is really; nor 
does it appear very probable it will be discovered, 
at least for some years to come. 
Taking one of these most beautiful appendages 
of the tree in our hands, we may ask, What is 
the exact cause of the colour so exquisitely in- 
laid in the striped petals of this flower? Some 
thoughts, which occupied us on a previous page, 
will perhaps help us to answer the inquiry. We 
there found a poor imprisoned potato putting out 
a shoot in the dark, which was as white as the 
most delicate flower, but as soon as it crept into 
the light becoming all of a sudden of a deep 
green. Why then do not white flowers turn to 
green when exposed to light? Let the reader call 
to mind what was said about the little cells which 
make up the whole structure of the plant. Some 
of these little cells contain a substance which, 
when exposed to light, undergoes various changes, 
