40 BULLETIN 1064, t\ S. DEPARTMENT OF AGRICULTURE. 
unknown. A more intimate knowledge of the substances of the great- 
est significance in resin production — as, for instance, the effects of the 
constitution of the soil — might have a marked influence on future 
practice. This has been found to be the case with fruit culture, as a 
result of the work on the effects of the carbon-nitrogen ratio upon 
vegetative and reproductive responses. 40 Indeed, as has been sug- 
gested by Dr. W. D. Bancroft, chairman of the division of chemistry 
and chemical technology of the National Eesearch Council, who 
selected oleoresin production as an example of an important present- 
day problem, the understanding of this subject appears to involve 
cooperative work by a botanist, a microscopist, an organic chemist, 
and a colloid chemist. Much valuable information on oleoresin has 
already been collected by the Bureau of Chemistry and by different 
units of the Forest Service, and with the timber on the Florida Na- 
tional Forest available for experiment, the opportunities for carrying 
on further research are exceptionally good. That the future need in 
this direction is recognized and that plans (in the carrying out of 
which microscopically obtained data can unquestionably be of serv- 
ice) are being formulated, is indicated in the following statement of 
Col. \V. G. Greeley. Forester : 41 
One of the things which must be worked out as part of our general progress 
in forest conservation is a system of extracting gum turpentine which will make 
this industry and its valuable commercial products a permanent resource of 
the Southern States. We must develop a plan for tapping second-growth timber, 
somewhat along the lines used in France but adapted to commercial require- 
ments in the United States, under which this can be a continuous forest indus- 
try, obtaining yields of gum from the same trees for 20 or 30 years, right up 
to the time when they are cut and converted into lumber. Without some 
method of this nature the gum turpentine industry will soon cease to exist. 
I am hopeful that the Forest Service can extend the instructive experiments in 
various methods of conservative chipping and cupping which you e have already 
initiated on the Florida National Forest in order to work out completely a 
plan of tapping second-growth timber without injury which can be adopted 
commercially by the owners of pine land throughout the South. 
SUMMARY. 
The results of this work and of the other earlier and current ex- 
periments of the Forest Service clearly demonstrate that those 
methods which conserve the vitality of the tree and its responsive 
power, under stimulation such as is given by turpentining, insure 
the greatest production of oleoresin. The process of turpentining 
is not merely a draining out of the gum already formed ; it is a col- 
lection of the oleoresin constantly being manufactured by the tree. 
*° Kraus. E. J., and IT. R. Kraybill, Oregon Agrie. College, Exper. Station. Bulletin 149, 
1918. 
41 Fur. Serv. Bui., Jan. 3, 1921. 
42 That Is, Florida National Forest organisation. 
