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. 
No 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 up. Poor turpentining methods which kill or dry-face 
the timber, may produce some degrade due to pitch-streak forma- 
tion, decay, or excessive insect attack, but this is for the most part 
unnecessary. The fact that many lumber companies are turpen- 
tining their own timber is also a pertinent argument for the practice. 
