16 TREE PRUNING. 



Authorities agree on the influence which trees exert 

 on the climate, the watercourses and the fertility of 

 the soil. Economically indispensable trees are not 

 less important in their influence on the health of man. 

 Trees purify the air we breathe by absorbing noxious 

 gases, and it is clearly for the interest of the com- 

 munity to preserve and multiply the forests, which 

 protect the human race from many evils. 



