THE BURNING BUSH 97 



appear, and grows red or blue, or what not colour, according 

 to the acids with which it comes in contact. This colour- 

 ing matter plays a part which is little understood. But some 

 of its functions are known. It has beyond doubt a pro- 

 tective purpose. A walnut-tree in spring has almost an 



FLOWERS OF TULIP-TREE 



autumnal appearance, so red are the young leaves. This 

 same ruddy tint invades the young rose leaves and those of 

 many another tree. The colour in this case protects the 

 tender green from excessive burning from the sun and 

 screens the chlorophyll which is the tree's life-blood. This 

 colouring is best seen on the skin of apples and other fruits. 

 It will make its appearance even on pure white roots if they 

 are exposed to the sun. It is present in varying force in 



