they proved
useful to the plant by attracting insects or other living creatures, it is
obvious that the advantage would lie with those plants which could put
forth an animal sexual odor of agreeable character, since such an odor
would prove fascinating to animal creatures. We here have a very simple
explanation of the fundamental identity of odors in the animal and
vegetable worlds. It thus comes about that from a psychological point of
view we are not really entering a new field when we begin to discuss the
influence of perfumes other than those of the animal body. We are merely
concerned with somewhat more complex or somewhat more refined sexual
odors; they are not specifically different from the human odors and they
mingle with them harmoniously. Popular language bears witness to the
truth of this statement, and the normal and abnormal human odors, as we
have already seen, are constantly compared to artificial, animal, and
plant odors, to chloroform, to musk, to violet, to mention only those
similitudes which seem to occur most frequently.

The methods now employed for obtaining the perfumes universally
used in civilized lands are three: (1) the extraction of
odoriferous compounds from the neutral products in which they
occur; (2) the artificial preparation of naturally occurring
odoriferous compounds by synthetic processes; (3) the manufacture
of materials which yield odors resembling those of pleasant
smelling natural objects. (See, e.g., "Natural and Artificial
Perfumes," _Nature_, December 27, 1900.) The essential principles
of most of our perfumes belong to the complex class of organic
compounds known as terpenes. During recent years a number of the
essential elements of natural perfumes have been studied, in many
cases the methods of preparing them artificially discovered, and
they are largely replacing the use of natural perfumes not only
for soaps, etc., but for scent essences, though it appears to be
very difficult to imitate exactly the delicate fragrance achieved
by Nature. Artificial musk was discovered accidentally by Bauer
when studying the butyltoluenes contained in a resin extractive.
Vanillin, the odoriferous principle of the vanilla bean, is an
aldehyde which was first artificially prepared by Tiemann and
Haarmann in 1874 by oxidizing coniferin, a glucoside contained in
the sap of various coniferae, but it now appea