THE SCHOOL BOOK OF 

 FORESTRY 



CHAPTER I 



HOW TREES GROW AND MULTIPLY 



The trees of the forest grow by forming new 

 layers of wood directly under the bark. Trees 

 are held upright in the soil by means of roots 

 which reach to a depth of many feet where the 

 soil is loose and porous. These roots are the sup- 

 ports of the tree. They hold it rigidly in posi- 

 tion. They also supply the tree with food. 

 Through delicate hairs on the roots, they absorb 

 soil moisture and plant food from the earth and 

 pass them along to the tree. The body of the 

 tree acts as a passage way through which the 

 food and drink are conveyed to the top or crown. 

 The crown is the place where the food is digested 

 and the regeneration of trees effected. 



The leaves contain a material known as chloro- 

 phyll, which, in the presence of light and heat, 

 changes mineral substances into plant food. 



Chlorophyll gives the leaves their green color. 



11 



