2. Large: number arranged alternately—eim. 
3. Angles (of divergence. 
4. Adaptation in leaf arrangement. Influenced by 
environment. 
Two modes of distribution— 
1. Phyllotaxy, distribution along individual stem. 
2. Distribution with reference to plant as a whole. 
(1) Primarily a light relation. 
(2) Comparison of different trees, elm, Nor- 
Way) imaples sieatr snaple, Led maple, 
silver maple, locust. 
Color of foliage leaves. 
Majority green; due to chlorophyll. 
Light necessay for production of chlorophyll. _ 
Other colors; red (Rosa rubrifolia), purple (purple bar- 
berry, hazel, beech, birch), yellow (golden oak, elder). 
All possess chlorophyll in addition. 
Autumn colors. 
1. More marked in some trees than in others. 
2. Red, in red maple, red and scarlet oak, sourwood. 
3. Yellow in sugar maples, poplars, hickories. 
4. Sweet gum. 
5. Red and purple suffused in cell sap as in cells of red 
beet. | 
6. Yellow due to disappearance and degeneration of 
chlorophyll. 
7. Yellowing of crops. 
8. Blanching grass. Celery. 
g. Theories concerning autumn coloring. 
Ist, attributed to 
of JETRO. 
2. Action of more oblique rays of sun. 
3. Diminishing water supply. 
2nd, question obscure one. 
Low temperature. 
Declining actvities of leaf. 
Different soil. 
Different climate. 
3rd, North American forests. 
0. 
