640 SOME OF THE POSSIBILITIES OF ECONOMIC BOTANY. 
VUII.—FRAGRANT PLANTS. 
Another illustration of our subject might be drawn from a class of 
plants which repays close study from a biological point of view, namely, 
those which yield perfumes. 
In speaking of the future of our fragrant plants we must distinguish 
between those of commercial value and those of purely horticultural 
interest. The former*will be less and less cultivated in proportion as 
synthetic chemistry by its manufacture of perfumes replaces the natu- 
ral by the artificial products, for example, coumarin, vanillin, nerolin, 
heliotropin, and even oil of wintergreen. 
But do not understand me as intimating that chemistry can ever 
furnish substitutes for living fragrant plants. Our gardens will always 
be sweetened by them, and the possibilities in this direction will con- 
tinue to extend both by contributions from abroad and by improve- 
ment in our present cultivated varieties. Among the foreign acquisi- 
tions there are the fragrant species of Andropogon. Who would suspect 
that the tropical relatives of our sand-loving grasses are of high com- 
mercial value as sources of perfumery oils? 
The utility to the plant of fragrance in the flower and the relation of 
this to cross-fertilization, are apparent to even a casual observer. But 
the fragrance of an aromatic leaf does not always give us the reason 
for its being. 
it has been suggested for certain cases that the volatile oils escaping 
from the plants in question may, by absorption, exert a direct influence 
in mitigating the fierceness of action of the sun’s rays. Other explana- 
tions have also been made, some of which are even more fanciful than 
the last. 
When however one has seen that the aromatic plants of Australia 
are almost free from attacks of insects and fungi, and has learned to 
look on the impregnating substances in some cases as protective against 
predatory insects and small foes of all kinds, and in others as fungi- 
cidal, he is tempted to ask whether all the substances of marked odor 
which we find in certain groups of plants may not play a similar réle. 
Itis a fact of great interest to the surgeon that in many plants there 
is associated with the fragrant principle a marked antiseptic or fungi- 
cidal quality; conspicuous examples of this are afforded by species of 
Hucalyptus, yielding eucalyptol, Styrax, yielding styrone, Thymus yield- 
ing thymol. It is interesting to note too that some of these most 
modern antiseptics were important constituents in the balsamic vul- 
neraries of the earliest surgery. 
IX.—FLORISTS’ PLANTS. 
Florists’ plants and the floral fashions of the future constitute an en- 
gaging subject which we can touch only lightly. It is reasonably clear 
that while the old favorite species will hold their ground in the guise 
