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 21 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. 
aa Herty, C. H., ,: The Turpentine Industry in the Southern States." Jour. Franklin 
Institute, March, 1916, p. 362. 
17 See footnote p. 3. 
"For. Serv. Bui. 90, p. 28. 
