e branches upon the study of
which you are entering. I may teach you a very little directly, but I
hope much more from the trains of thought I shall suggest. Do not expect
too much ground to be covered in this rapid survey. Our task is only
that of sending out a few pickets under the starry flag of science to the
edge of that dark domain where the ensigns of the obstinate rebel,
Ignorance, are flying undisputed. We are not making a reconnoissance in
force, still less advancing with the main column. But here are a few
roads along which we have to march together, and we wish to see clearly
how far our lines extend, and where the enemy's outposts begin.

Before touching the branches of knowledge that deal with organization and
vital functions, let us glance at that science which meets you at the
threshold of your study, and prepares you in some measure to deal with
the more complex problems of the living laboratory.

CHEMISTRY. includes the art of separating and combining the elements of
matter, and the study of the changes produced by these operations. We can
hardly say too much of what it has contributed to our knowledge of the
universe and our power of dealing with its materials. It has given us a
catalogue raisonne of the substances found upon our planet, and shown how
everything living and dead is put together from them. It is
accomplishing wonders before us every day, such as Arabian story-tellers
used to string together in their fables. It spreads the, sensitive film
on the artificial retina which looks upon us through the optician's lens
for a few seconds, and fixes an image that will outlive its original. It
questions the light of the sun, and detects the vaporized metals floating
around the great luminary,--iron, sodium, lithium, and the rest,--as if
the chemist of our remote planet could fill his bell-glasses from its
fiery atmosphere. It lends the power which flashes our messages in
thrills that leave the lazy chariot of day behind them. It seals up a
few dark grains in iron vases, and lo! at the touch of a single spark,
rises in smoke and flame a mighty Afrit with a voice like thunder and an
arm that shatters like an earthquake. The dreams of Oriental fancy have
become the sober facts of our every-day life, and the chemist is the
magician to whom we owe them.

To return to the colder scientific aspect of chemistry. It has shown us
how bodies stand affected to each other through an almost boundless range
of c