OLEORESIN PRODUCTION. 7 
It is both from the horizontally extended fusiform rays, as ex- 
posed on a freshly cut tangential surface, and the vertically extended 
parenchyma aggregates, as exposed on the cross section, at the streak, 
that the droplets of oleoresin may be seen to exude. Large nuclei 
are often to be seen in these cells, as well as accumulations of starch 
grains. Tannin is also reported to be associated with resin forma- 
tion. 12 The vertical and horizontal systems of resin-producing 
parenchyma are more or less united, since they frequently cross 
each other. The method of turpentining which keeps these cells 
active and which provides suitable stimulation to insure their great- 
est productivity without undue injury will give the highest and best 
yield of oleoresin over a period of years. In the discussion in the 
following pages of the results from the experiments, the methods 
used were judged, not alone by the yield obtained, but also by the 
amount and type of the wood tissue produced, as indicative of the 
vitality and responsive power of the trees. In each case the wood 
tissue produced by neighboring, comparable, unturpentinecl trees 
growing under similar environment was studied and used as a check 
upon the judgments formed. 
METHODS OF STUDY. 
COLLECTION AND TREATMENT OF MATERIAL. 
The first material to be studied was in the form of fresh chips or 
pieces collected by the writer from the living trees and put in corked 
bottles. This material was examined within a few hours after cut- 
ting. Specimens shipped to the laboratory at Madison periodically 
during the season were handled in the same way, with the exception 
that sometimes moistened cotton was put in the bottles to prevent the 
drying out of the specimens. Later, fixing solutions were used, and 
the chips or increment borings were placed in the solution selected as 
soon as cut. These were kept for a length of time which necessarily 
varied with circumstances, washed with water, and stored in glycerine 
and alcohol. The fixatives used were: (1) Mercuric chloride, a satu- 
rated solution in 90 per cent alcohol; (2) mixture of a saturated 
solution in 90 per cent alcohol of mercuric chloride (3 parts) and of 
picric acid (1 part) ; (3) chrome-acetic fixative, consisting of a mix- 
ture, in 100 cubic centimeters of water, of 1 per cent glacial acetic 
acid and 0.7 per cent chromic acid. 
13 Haas and Hill: "Introduction to the Chemistry of Plant Products," Vol. I, 3d Ed. 
1921. pp. 195, 217. " In Pinus it is stated that the amount of tannin varies with that of 
the resin rthus in the spring it was found that as the tannin decreased in amount so the 
resin increased. * * * That starch frequently is contained in the same cells with tannin 
suggests a connection between the two and it is not impossible that the starch may con- 
tribute glucose for the constitution of the tannin. The cells surrounding the epithelium 
of resin ducts contain tannin and starch." Wiesner " Die Rohstoffe des Pflanzenreiches " 
concluded that tannin was an intermediate product in resin formation. 
