fill 



it 



a\\\\\\\\ \ 



LO. /3 Pin us 



Fio. /t. Pin us 



Plate JET 



PLATE VI. 



Fig. 13. Cross sections of Pinus strobus (White Pine) growing on the hilltop 

 at region 3, Aliquippa district. Shows the tendency toward the narrowing of 

 annual rings. 



Fig. 14. Cross sections of Pinus strobus growing on the mountains near 

 State College, Pennsylvania, showing wide and rather uniform annual rings. 

 Here the conditions for growth were favorable. 



