154 R. T. BAKER AND H. G. SMITH. 
Chemistry of the Leaf Oil.—_Somewhat comprehensive 
chemical results are here recorded for the leaf oil of this 
species. The material was all distilled at the Museum, and 
was gathered over a great extent of territory. The data 
obtained represent a period of over nine years. The object 
of this was to ascertain, from material belonging to one 
well defined species, the influence of locality, soil and 
climate, on the chemical constituents of the tree. It has 
been advanced by some writers that these influences are 
largely predominant with plants generally, and that, there- 
fore, constancy of results can hardly be expected. 
Our extensive researches on the oils of the Hucalypts, 
showed a remarkable constancy in the chemical con- 
stituents of individual species of that genus, so much so, 
that it was possible to advance the statement that material 
obtained from the same species of Kucalyptus would always 
give practically the same results, no matter where 
grown. This has been often questioned, but subsequent 
investigations have confirmed that statement. With the 
oils of the Callitris the same practical uniformity exists, 
although perhaps not so markedly as with the EKucalypts, 
as the rotation figures show more variation. This difference 
is largely accounted for by the varying amount of fruits 
present on the material distilled, as the oil from the fruits 
of most species of Callitris, has the opposite rotation to 
that obtained from the leaves, even when collected from 
the same tree, and the amount of ester is less also; the 
terpenes are, however, the same, only with opposite rota- 
tions. This fact is of considerable scientific interest, and 
the peculiarity has been conclusively proved in several 
instances, by carefully removing the fruits from the leaf 
branchlets, and distilling them separately. It was some- 
what late in the research before this fact was discovered, 
so that the separate determination was not made with 
