OLEORESIN PRODUCTION. 41 
This production of gum by the tree is greatly increased as a result of 
the stimulation of the wound or face cut. 
The institution of cupping, in place of boxing, made it possible to 
eliminate the unnecessary injury to the tree caused by cutting the 
box, and hence was a marked advance in the direction of improved 
operation. 
The jDroper placing of faces with reference to the size and confor- 
mation of the tree, and the maintenance of bark bars of sufficient 
width between faces, are matters of fundamental importance, which 
too often are neglected in practice. These matters if not cared for 
involve waste and loss throughout the operation. 
The fact that it is unprofitable to turpentine too small trees, at 
least by present commercial methods, has been demonstrated beyond 
question. 
The practice of cutting a streak in advance of the regular season's 
chipping on a virgin or first year operation appears to be productive 
of an increased early yield, which is of practical importance. This 
effect, as has been clearly shown, is not produced by the induced resin 
passages, formed at once as the immediate result of the streak, but 
presumably is due to the wound stimulus given to the resiniferous 
tissue already present. 
The following effects of turpentining on the structure of the wood 
have been pointed out : 43 
The structure of the annual rings of the wood formed before tur- 
pentining was not found to be visibly affected as a result of the tur- 
pentining, although the activities and responses of the living paren- 
chyma cells in the outer layers of the sapwood already present in the 
immediate vicinity of the wound were undoubtedly stimulated by it. 
It was demonstrated that the resin passages of a considerable number 
of these outer sapwood rings contributed a very significant portion 
of the yield of oleoresin. 
The structure of the wood produced after wounding was con- 
siderably modified, especially in the region immediately above the 
face. The effect in a tangential or circumferential direction was 
relatively slight, being hardly noticeable at a distance of 2 or 3 inches 
to the side of the wound. In all material the number of resin pas- 
sages formed was greatly increased. The resin passages were formed 
earlier in the ring than normally. They varied from about the same 
diameter as that of the normal resin passages to rarely larger and 
frequently smaller diameters. The response to the wound stimulus, 
particularly in respect to the increased number of resin passages 
formed, was observed to be greatest within about 1 foot above the 
43 See also Gerry, E., " Proper Methods of Turpentining:," Sei. Am. Sup. 2176, Sept. 15, 
1917 ; and Gerry, E., " Production of Crude Gum by the Pine Tree," Naval Stores, p. 147, 
1921. 
