ing the depressions.

In side lighting, two lights may be used. Better results are often
obtained, however, by using only one light, such as a spotlight, the
beam of which can be controlled to best advantage.

Transmitted light is used in cases in which the skin has peeled off or
in which the dermis has been removed, cut, and scraped thin so that
light will go through. The prepared skin is placed between two pieces
of glass pressed together in order to flatten the skin or dermis and
remove creases. By trimming some of the surplus skin or dermis,
especially at the top, it may be more easily flattened. After the
glass is properly mounted in front of the camera, the lights are
placed behind it and light is directed through the skin. The ridge
detail is brought into focus on the ground glass. Before the picture
is actually taken it is suggested that the ground glass be checked by
first using one light and then two lights to see which is more
effective.

There will be instances in which the second layer of skin, cut and
scraped thin enough to flatten out, fails when dry to have a
sufficient contrast between ridges and depressions for purposes of
photographing. The same piece of skin when soaked in xylene will show
a marked contrast, which it loses on drying. This difficulty is
overcome by photographing the skin while in solution, which can be
done by placing the skin in a test tube or a small bottle of a size to
keep the skin upright and the ridges toward the camera. The test tube
or bottle is then filled with xylene.

If the skin is sufficiently thin, transmitted light may be used.
Should it be found, however, that transmitted light is not effective,
then direct light may be tried and the results checked in the ground
glass (fig. 401).

When photographing a small curved surface such as a test tube, direct
lighting will usually create a high light. If the high light as shown
in the ground glass is over the ridge detail on the skin, a poor
photograph will result. If the high light cannot be removed by
rearranging the lights, then reflected light should be tried.

In order to effect reflected light a large piece of white paper,
cardboard, or similar material is used. A hole is cut in the center of
the paper or cardboard. This must be big enough for the camera lens to
protrude through. The ends of the paper or board are curved toward the
skin or finger to be photographed. The lamps which are to be used are
placed facing