old Leeuwenhoek, peeping with his octogenarian eyes through the
minute lenses wrought with his own hands, had long ago seen the "pipes,"
as he called them,--was hardly known at all. The minute structure of
the viscera lay in the mists of an uncertain microscopic vision. The
intimate recesses of the animal system were to the students of anatomy
what the anterior of Africa long was to geographers, and the stories of
microscopic explorers were as much sneered at as those of Bruce or Du
Chailly, and with better reason.

Now what have we come to in our own day? In the first place, the minute
structure of all the organs has been made out in the most satisfactory
way. The special arrangements of the vessels and the ducts of all the
glands, of the air-tubes and vesicles of the lungs, of the parts which
make up the skin and other membranes, all the details of those complex
parenchymatous organs which had confounded investigation so long, have
been lifted out of the invisible into the sight of all observers. It
is fair to mention here, that we owe a great deal to the art of minute
injection, by which we are enabled to trace the smallest vessels in the
midst of the tissues where they are distributed. This is an old artifice
of anatomists. The famous Ruysch, who died a hundred and thirty years
ago, showed that each of the viscera has its terminal vessels arranged
in its own peculiar way; the same fact which you may see illustrated in
Gerber's figures after the minute injections of Berres. I hope to show
you many specimens of this kind in the microscope, the work of English
and American hands. Professor Agassiz allows me also to make use of
a very rich collection of injected preparations sent him by Professor
Hyrtl, formerly of Prague, now of Vienna, for the proper exhibition
of which I had a number of microscopes made expressly, by Mr. Grunow,
during the past season. All this illustrates what has been done for the
elucidation of the intimate details of formation of the organs.

But the great triumph of the microscope as applied to anatomy has
been in the resolution of the organs and the tissues into their simple
constituent anatomical elements. It has taken up general anatomy where
Bichat left it. He had succeeded in reducing the structural language of
nature to syllables, if you will permit me to use so bold an image. The
microscopic observers who have come after him have analyzed these into
letters, as we may call them,--the sim