266 
NATURE FOR ITS OWN SAKE 
Light-trans- 
formations. 
Swift color- 
changes. 
which it runs over daily with the shifting of 
the sun. Light transforms all things, and we 
have already seen what changes it may produce 
upon the foliage of a mountain-top. The 
leaves are heightened, deepened, bleached, or 
distorted, according to their texture or light- 
reflecting capacity. Often the green of a tree- 
top is turned to cold gray under a noonday 
sun, and at sunset, when the trunks of the 
trees are in shadow and their tops in full sun- 
light, everyone knows what a sharp contrast 
appears. The top is yellow, the body dark 
green. If the tree has a glossy leaf, the whole 
top may be a mass of reflected light. The 
tall tulip, the sycamore, or the chestnut at 
evening, with its loftiest leaves apparently 
changed into small shields of flashing light, is 
not an uncommon spectacle. 
I fear that many of us have small conception 
of the changes that may take place in a green 
leaf in the course of a single day. It is green 
in our hand, and we naturally think it must be 
green on the tree ; and so the easy conclusion is 
reached that leaves in summer are green and 
never anything else. But they are seldom the 
same green for any length of time. I once tried 
to keep a record from day to day of the color- 
