have formed the basis of a
communication to the American Academy of Arts and Sciences, in which many
new observations have been added to our knowledge of this most complicated
structure. But figures drawn from images seen in the field of the
microscope have too often been known to borrow a good deal from the
imagination of the beholder. Some objects are so complex that they defy
the most cunning hand to render them with all their features. When the
enlarged image is suffered to delineate itself, as in Dr. Dean's views of
the _medulla oblongata_, there is no room to question the exactness of the
portraiture, and the distant student is able to form his own opinion as
well as the original observer. These later achievements of Dr. Dean have
excited much attention here and in Europe, and point to a new epoch of
anatomical and physiological delineation.

The reversed method of microscopic photography is that which gives
portraits and documents in little. The best specimen of this kind we have
obtained is another of those miracles which recall the wonders of Arabian
fiction. On a slip of glass, three inches long by one broad, is a circle
of thinner glass, as large as a ten-cent piece. In the centre of this is a
speck, as if a fly had stepped there without scraping his foot before
setting it down. On putting this under a microscope magnifying fifty
diameters there come into view the Declaration of Independence in full, in
a clear, bold type, every name signed in fac-simile; the arms of all the
States, easily made out, and well finished; with good portraits of all the
Presidents, down to a recent date. Any person familiar with the faces of
the Presidents would recognize any one of these portraits in a moment.

Still another application of photography, becoming every day more and more
familiar to the public, is that which produces enlarged portraits, even
life-size ones, from the old daguerreotype or more recent photographic
miniature. As we have seen this process, a closet is arranged as a
camera-obscura, and the enlarged image is thrown down through a lens above
on a sheet of sensitive paper placed on a table capable of being easily
elevated or depressed. The image, weakened by diffusion over so large a
space, prints itself slowly, but at last comes out with a clearness which
is surprising,--a fact which is parallel to what is observed in the
stereoscopticon, where a picture of a few square inches in size is
"extended" or dilut