8 BULLETIN 1064, U. S. DEPARTMENT OF AGRICULTURE. 
SECTIONING AND MOUNTING. 
Relatively thin sections (10 to 48 microns) were made from the 
greater number of the specimens studied. For this purpose a sliding 
microtome of the Jung type with the Thomson modification was 
used. Some observations were made with a hand lens on smoothly 
cut surfaces. The sections to be preserved or photographed were 
stained with safranin (water-alcohol mixture), dehydrated with 
alcohol, cleared with xylol, and mounted in Canada balsam. Micro- 
scopic examinations were also made of microtome or hand sections 
temporarily mounted in glycerine alcohol (50-50 mixture). 
AMOUNT OF MATERIAL. 
Samples were obtained each month during the 1916 and 1917 
seasons, from 15 trees, 5 from each of the three experimental plots. 13 
Specimens were also examined at the end of each season from 50 
trees on each plot and from 50 unturpentined trees from the same 
locality. In addition to this, considerable material was collected 
from Bogalusa, La. ; Kokomo and Gulfport, Miss. ; Daytona, Boni- 
fay, and the Forest Service experiments and leases near Camp 
Pinchot, Fla. More than 4,500 microscopic mounts were prepared 
and examined. 
PROCESS OF TURPENTINING. 
METHODS OF WOUNDING OR SCARIFYING THE TREES. 
In ordinary methods of turpentining the oleo resin is made to flow 
from the tree by periodically cutting a wound or streak through the 
bark and for a variable distance into the sapwood. In the United 
States the cut or streak is generally made in the form of a some- 
what flattened V, the point or peak of which is at the center of the 
face. (PI. I, fig. 4.) The wound used by the French is different 
in shape (PI. I, fig. 6), and smaller. The Germans recently have 
been practicing modifications of the American system. 
Except for the general type of face used, the commercial practice 
of turpentining is not standardized in the United States. The size 
of the faces used, the amount of bark bars between faces, and the 
dimensions of the streak or wound cut each week, show marked 
differences in different operations. The depth of the weekly chip- 
ping may vary from one-half inch to 1£ inches (bark not included), 
and the height of the chipping from one-half inch to 1 inch, or 
enough, as some operators say, to " keep ahead of the lightwood." 1 * 
13 When more than one face was on a tree each face was indicated by a letter descrip- 
tive of its general position with reference to points of the compass, as N., S., E., W. 
(See, for instance, tree 1, fig. 1.) 
" See p. 31. 
