THE LEAVES 67 



the leaves of the oak and maple immediately after 

 the buds open in the spring, and compare with that 

 of the mature organs. Compare also the colors of 

 ripe and unripe fruits, such as apples, tomatoes, 

 berries, plums, and peaches. 



78. Autumnal colors. — The colors of autumnal 

 leaves are very striking, not only because of their 

 depth and brilliancy, but because they appear on 

 so many leaves and so many plants at the same 

 time. Furthermore, the plants which show colors 

 most notably are trees which are large and prominent 

 features of the landscape. These colors embrace a 

 large number of shades and tints of yellow, red, and 

 purple, and they are probably formed from the sugar 

 in the cells, and by the breaking down of the green 

 color into yellows and browns. Yellow colors are 

 also formed independently, or appear most strikingly 

 in dying leaves. The actual changes of color in at 

 least one species should be followed through the 

 months of September and October, as well as the 

 colors of the same species when the buds open in 

 the following spring. Although the autumnal colors 

 of every species show some diversity, yet the keynote 

 is fairly constant. The birches are a golden yellow, 



