10 BULLETIN 1064, U. S. DEPARTMENT OF AGRICULTURE. 



passages are differentiated in the annual ring beginning to form for 

 that year. An instance of a yield obtained by the end of April, rang- 

 ing from 16 to 24 barrels of gum per month, per 10,000 cups, or " crop," 

 was observed on a virgin operation where at the time no new resinifer- 

 ous tissue had been formed. Therefore it is apparent that the resin 

 passages already present in the outer sapwood of the round timber 

 play a significant part in producing the gum obtained. 



USE OF THE "ADVANCE STREAK." 



A practice, the consequences of which are as yet not fully ex- 

 plained, but which appears to produce desirable results, is that of 

 cutting a streak or wound some time before regular chipping begins. 15 

 The results of such scarification were pointed out by Dr. C. H. 

 Herty in 1911. In the early experiments, made to demonstrate the 

 advantages of replacing the box system by the cup system, the boxes 

 were cut in winter and cornered in late winter. The first streak was 

 made somewhat later along the upper edge of the wound made by 

 cornering. In the case of the cupped trees, on the other hand, no 

 such severe wound was inflicted. The trees, however, were cor- 

 nered — that is, the bark and some of the wood were removed in order 

 to obtain a suitable surface for the gutters. The first streak was 

 cut at a little distance above the curved rim of the cornered surface. 

 The ends or corners of the streak were farther above the cut surface 

 than the peak and consequently did not reach directly to this open 

 wound made some time before. Until May the yield of gum was 

 notably less in the cupped trees than in the boxed trees, which had 

 received a more intense wound stimulus. 



Wounding the outer sapwood, therefore, in this manner (or even 

 less severely, as is the practice on the Florida National Forest and 

 in India) appears to have a very definite effect on the early yield of 

 gum. It was estimated by one operator, for instance, that this prac- 

 tice gained for him, on one operation, a total of $500,000 in one 

 year. 16 This practice, strongly advocated by Dr. Herty, was repeat- 

 edly employed with success. The theoretical explanation of it, 

 advanced by him on the basis of the results of Tschirch's 17 investiga- 

 tions on other resin-yielding trees, was however not in accord with 

 the facts. His deduction was as follows : 



Immediately after cornering (late winter) the formation of secondary resin 

 ducts begins at all points of the cut. Later when the tree is chipped, these 

 secondary ducts are opened along the full length of the cut and a good yield is 

 consequently at once obtained. 18 



15 For. Serv. Bui. 90, p. 28. 



18 Herty, C. H., ' " The Turpentine Industry in the Southern States." Jour. Franklin 

 Institute, March, 1916, p. 362. 



17 See footnote p. 3. 



18 For. Serv. Bui. 90, p. 28. 



