OLEORESIN PRODUCTION. 45 



creases in 1917 were less indicative, but increases were more signifi- 

 cant, since normal diameter growth was relatively low in that year. 



It was observed that, regardless of the method used, the response, 

 after turpentining, of trees with very narrow annual rings often 

 was to produce much wider rings than before; whereas the trees 

 with exceedingly wide rings and very heavy summer wood often 

 showed marked reduction in the wood formed after turpentining. 



A tendency toward more vigorous responses was observed on the 

 south side of trees, as contrasted with the north side. 



Very great variation in wood formation and productive power 

 was observed in individual trees in the same environment. No satis- 

 factory means was found, however, of positively determining in 

 advance the productive power of a tree. Marked variations in the 

 wood formation on different sides of a tree, at different parts of 

 the streak, and at different heights, were noted. The study of 

 specimens obtained month by month at different heights was there- 

 fore more enlightening in many respects than observations made only 

 at the end of the season. 



MISCELLANEOUS OBSERVATIONS. 



No consistent relation between width of ring and number of resin 

 passages resulted from an analysis of the data available on this 

 subject. 



Xo indication of a structure corresponding in any way to the 

 " resinogene Schicht " of Tschirch was observed. 



The first formation of wood in the region of the trunk where tur- 

 pentining is carried on was observed, in 1916 and 1917, to take place 

 not earlier than April 8 to 10; and from that time on in different 

 trees it continued until by the middle of May it had begun in prac- 

 tically all trees. Wood cells or tracheids for the most part formed 

 before resiniferous tissue. 



The first formation of resiniferous tissue occurred between the 

 middle of April and the end of May. 



Finally, turpentining gives an additional product and profit from 

 the forest before the trees are cut into lumber. This gain may 

 be obtained, at least in the case of well-managed, large, mature tim- 

 ber, without reducing its strength, or appreciably degrading the 

 lumber. The inch or so of the outer sapwood involved in the 

 process of turpentining is removed in the slabs and edgings when the 

 logs are cut lip. Poor- turpentining methods which kill or dry-face, 

 Che timber, may produre some degrade due to pitch-streak forma- 

 tion, decay, or excessive insect attack, but this is for the most pint 

 unnecessary. The, fact that many lumber companies are turpen 

 tining their own timber is also a pertinent argument for the practice, 



