THE PRINCIPLES OF FORESTRY 187 



may soon die and drop off. Those in the open grow large 

 because of the light all about them (Fig. 93). Which would 

 produce clear lumber and which would be knotty? 



EXERCISE. Rings of Wood. Have some one bring to 

 school a circular section cut across the end of a tree trunk, 



I 



FlG. 95. Method of mounting wood samples for study. ( Agricultural Education.) 



showing the rings of wood. Each ring represents one season 

 of growth. Count them. Are some wider than others? 

 Are the wide rings indications of favorable or of unfavorable 

 seasons of growth ? Notice the dark heart-wood in the center 

 and the light colored sap-wood near the bark. Figure 95 

 represents a good method of saving samples for future study. 



