132 NATURAL HISTORY OF THE FARM 
Optional Study 4. Autumnal Coloration and Leaf Fall 
Probably the grandest phenomenon of nature that is pecu- 
liar to our northern latitude, is the coloration of the woods 
in autumn. All marvel at the display. Few observe it 
carefully. Itis the object of this study to direct attention to 
some of the external features of it: the mechanical prepara- 
tion of the leaf for its fall, the changing pigments of the 
residual leaf contents, and the relation of these changes to 
temperature and rainfall, etc. The whole process is a 
wonderful adaptation to meet winter conditions, and how 
admirably nature manages it! She first withdraws all food 
materials from the leaves into the stem and branches. Then 
she starts her wonderful display by elaborating bright pig- 
ments out of the residue. Then she casts the leaves off in 
an orderly fashion, developing breaking points at proper 
places. So she diminishes to a very small percentage the 
area of exposed evaporating surfaces, and thus she conserves 
moisture in the plant body through the long cold season. 
The changing hues of autumn are more or less accidental by- 
products of this process; but they are very beautiful. 
The work of this study should include serial observations 
on a dozen or more of the more brilliantly colored species, 
continued from the first appearance of an autumn tint until 
the last of the leaves have fallen. The same trees should be 
observed day by day, account being taken of the relevant 
weather conditions. Hence, trees, shrubs and vines near at 
hand should be chosen. Those on the lawn are apt to be as 
good as any, since ornamental planting in our day takes 
careful forethought for the autumnal display. 
