■ goy ~\ Herty — The Pine and its Products. 33 
wound the tree. If the tree is girdled it dies. What then is 
the limit of wounding to which it is necessary to subject the 
tree in order to get the most profitable yield, and beyond 
which it is unsafe to go ? It had been proved at Ocilla that 
the box was an unnecessary wound and that by its elimina- 
tion the yield could be increased. The next step then was to 
make comparative tests bearing upon the extent of the wound 
given in “chipping.” For the past two years such experi- 
ments have been conducted in Florida by the U. S. Forest 
Service, and by the courtesy of the Service I am enabled to 
tell you that results already obtained show that shallow chip- 
ping produces as much or eventually more crude turpentine 
than the customary deep chipping, while at least one year in 
three can be gained in the usual rate of ascent of the tree 
without diminishing the output. Still other experiments 
yielding most valuable results are in progress, all bearing 
upon more conservative wounding of the tree. None of these 
experiments are extreme, but all are rational modifications of 
present practices which will carry conviction when the details 
are published. 
Of an entirely different character from the experiments 
just mentioned, but of great scientific and practical value, 
are the recent studies of Prof. A. Tschirch, of Switzerland, on 
resin secretion. By the use of the microscope and suitable stains 
he has proven that the seat of resin production is in a'muci- 
laginous layer lining the inner walls of the resin ducts. In a 
later study, carried out upon a large number of trees, he has 
further demonstrated that while there are a limited number 
of “primary” resin ducts present in the untapped pine, by far 
the greater flow of resin proceeds from secondary ducts 
formed in the outer sap wood after the wounding of the tree. 
The resin from the “primary” ducts is a physiological pro- 
duct, that from the “secondary” a true pathological product. 
While many chemical studies have been made of the pro- 
ducts obtained by distillation of crude turpentine, only one 
detailed investigation is on record regarding the nature of the 
