OLEORESIN PRODUCTION. 6 
eter, and the preservation of the general health of the tree are 
considerations of fundamental importance. This is especially true 
with reference to the methods that are to be used in the future for 
turpentining smaller, second-growth trees. The need for wider 
knowledge and the practice of better methods is imperative in the 
United States, in order that this important and exceptional oppor- 
tunity for the production of naval stores shall not be wiped out or 
wasted by improper exploitation. 5 
The work covered was undertaken in order to obtain, by means 
of microscopic study, information on the changes which result from 
turpentining in the wood of the pines, which are the chief sources 
of naval stores. The advantages and disadvantages of different 
methods of operation were determined chiefly by examining speci- 
mens of the wood produced near the faces or scars. These specimens 
were usually cut just above the streak or surface of the last wound. 
Structures found on workings of different ages were also studied. 
The specimens furnished evidence which served as a check of con- 
siderable precision upon the more general means of comparison, 
such as amount of gum produced and percentages of dead and dry- 
faced trees caused by turpentining. Changes produced by turpen- 
tining which were registered in the internal anatomy of the pines 
were studied, not only in the completed annual ring at the end of the 
season, but also particularly in specimens obtained periodically 
throughout the year. The first material was cut before wood forma- 
tion began in the spring, and the development shown in fresh speci- 
mens cut each month thereafter was studied throughout the subse- 
quent growing season. The chief source of material was a coopera- 
tive experiment carried on at Columbia, Miss., where three methods 
of chipping were compared, 6 but specimens were also collected at 
other points in Mississippi and in Louisiana and Florida. 
An attempt was also made to determine the significance of certain 
observations made at the Forest Products Laboratory not in accord 
with views previously published, some of which were founded upon 
analogy rather than upon the study of native American species. 7 
OLEORESIN. 
The exudation obtained by the systematic scarification of the liv- 
ing pines, especially longleaf pine in the United States, is variously 
known as " oleoresin," " gum," " dip," and " scrape " (when hard- 
ened after long exposure to the air). From this substance rosin 
5 Approximately 75 per cent of the world's supply of grim turpentine is made in the 
United States. 
6 See pp. 12 to 25, 
7 Herty, C. H., " Relation of Light Chipping to the Commercial yield of Naval Stores," 
For. Ser. Bui. 90, 1911. Tschirch, A., " Die Harze u. d. Harzbehalter," 1900. 
