THE FOOD OF A TREE. 



13 



FIG. 8. The forest cover. Spruce in Bavaria, Germany. 



FIG. 9. Yearly growth of a branch of Horse Chestnut. The bands of wrinkles 

 mark the divisions between the growths of four successive years. The dis- 

 tance between these bands would never have been greater than it waa when 

 the branch was cut. 



