16 



BULLETIN 1064, U. S. DEPARTMENT OF AGRICULTURE. 



1916 many trees, 36 to 78 per cent, according to the position from 

 which the material was taken, showed no decrease in ring width 

 following turpentining. Also (see Table 3) 26 to 64 per cent showed 

 no decrease in the amount of summer wood formed, and the summer 

 wood appears to be one of the most readily affected structural fea- 

 tures. In Table 4, covering both 1916 and 1917, similar results 

 were shown; but the decreases in 1917, the second year of the opera- 

 tion, are somewhat larger in the case of this type of chipping than 

 they were in 1916. The size of the resin passages also decreased 

 somewhat as time went on. On the average a greater number of 

 resin passages per unit area was formed on this tract in 1917 than 

 on the double tract. In both 1916 and 1917, however, the number 

 on the narrow tract exceeded that on the standard. 



Table 2. 



-Comparison of the annual rings formed in round timber (19*5) and 

 turpentined timber (1916). 



Number and kind of speci- 

 mens. 



Trees showing increase 

 in ring width, 1916 

 (percentage of total 

 number).. 



Trees showing no de- 

 crease in ring width, 

 1916 (percentage of 

 total number). 



Trees showing decrease 

 in ring width, 1916 

 (percentage of total 

 number). 





Chips. 



Incre- 

 ments. 



Aver- 

 age. 



Chips. 



Incre- 

 ments. 



Aver- 

 age. 



Chips. 



Incre- 

 ments. 



Aver- 

 age. 







70 

 60 

 56 

 50 



70 

 62 

 41 



47 



64 

 36 



58 



95 



82 

 78 

 76 



95 

 73 

 57 

 67 



36 

 64 

 42 



5 



18 

 22 

 24 



5 



27 

 43 

 33 





64 

 26 

 44 









1 The narrow specimens showed more resin centers in the chips than were apparent in the standard and 

 double specimens. 



Note. — The increment borings were made on the tree at a distance of 2 to 3 inches from the face and at 

 the same height as the last streak. The chips we^re obtained at the cutting of the last streak. 



Table 3. — Comparison of the amounts of summer wood formed in the round 

 timber (1915) and the turpentined timber (1916). 



Number and kind of speci- 

 mens. 



Trees showing increase 

 m amount of summer 

 wood, 1916 (percent- 

 age of total number) . 



Chips. 



Incre- 

 ments. 



Aver- 

 age. 



Trees showing no de- 

 crease in amount of 

 summer wood, 1916 

 (percentage of total 

 number). 



Chips. 



Incre- 

 ments. 



Aver- 



Trees showing decrease 

 in amount of summer 

 wood, 1916 (percent- 

 age of total number). 



Chips. 



Incre- 

 ments. 



Aver- 

 age. 



20 trees, untapped . 

 50 trees, narrow I . . 

 50 trees, standard.. 

 50 trees, double 



i The narrow specimens showed more resin centers in the chips than were apparent in the standard and 

 double specimens. 



Note. — The increment borings were made on the tree at a distance of 2 to 3 inches from the face and at 

 the same height as the last streak. The chips were obtained at the cutting of the last streak. 



