ces seems to have come into use independently, in
widely separated countries, to produce the same effects, namely, to
refresh, renew, or sustain the physical and mental organism, and it was a
curious surprise to find, after they had all been thus long used, that
although each came from a different natural order of plants, the same
active principle--namely, caffeine--could be extracted in different
proportions from all. It is now still more curious, however, to find that
for centuries another plant, namely coca, yielding a different principle,
has been in use for similar purposes, the effects of which differ as
little from those of tea, coffee, etc., as these do among themselves. Yet
cocaine is chemically very different from caffeine, simply producing a
similar physiological effect in much smaller doses. All these substances
in their natural condition seem to be identical in their general
physiological effect, but idiosyncrasy, or different individual
impressibility or sensitiveness, causes a different action, as well in
quality as in degree from the different substances, upon some persons.

In order to throw a little additional light on the comparative activity
of the principal individuals of this group of substances, the following
trials were made. It is generally admitted, and is probably true, that
the same power in these agents which refreshes, recuperates, and sustains
in the condition which needs or requires such effects also counteracts
the tendency to sleep, or produces wakefulness when a tendency to sleep
exists; and, therefore, if a tendency or disposition to sleep could be
prevented by these agents, this tendency might be used as a measure of
their effects when used in varying quantities, and thus measure the
agents against each other for dose or quantitative effect. In this way
the proposition is to first measure coca against tea, then coffee against
guarana, and finally to compare the four agents, using pure caffeine as a
kind of standard to measure by.

An opportunity for such trials occurred in a healthy individual
sixty-five years old, not habituated to the use of either tea, coffee,
tobacco, or any other narcotic substances, of good physical condition and
regular habits, and not very susceptible or sensitive to the action of
nervines or so-called anti-spasmodics. Quantities of preparations of
valerian, asafoetida, compound spirit of ether, etc., which would yield a
prompt effect upon many individuals se