[1908 
Abstracts 
113 
rophylla. The collections of the oleo-resins from which the vol- 
atile oils were distilled were made at regular intervals throughout 
a complete season, March to November. A number of trees of 
eacb species were used. 
The optical rotation of the severel volatile oils obtained on 
distillation showed a marked variation. Those from Pinus Palus- 
tris were generally dextrorotatory, varying however from -f l° 
23' to +18° 18' (100mm. tube). One specimen showed a levo- 
rotation of — 7° 26'. The oils from Pinus Heterophylla were levo- 
rotatory, with one exception -f 0° 15', varying from — 7° 31* to 
-29° 26'. 
While these wide variations were noticed in the specimens from 
the individual trees, there was but slight variation in the speci- 
mens from the same tree throughout the season. 
