ightest indication
of the trephine opening appeared. To take, therefore, a skiagraph of a
brain through two thicknesses of skull, with our present methods, is an
impossibility. Even should the difficulty be overcome, it is very
doubtful whether there would be any possibility of discovering diseases
of the brain, since diseased tissues, such as cancer, sarcoma, etc., are
probably as permeable to the X rays as the normal tissues. Thus Reid
("British Medical Journal," February 15, 1896) states that a cancerous
liver showed no difference in permeability to the rays through its
cancerous and its normal portions.

Foreign bodies, such as bullets, etc., in the brain may be discovered
when our processes have become perfected. Figure 7 shows two buck-shot
skiagraphed inside of a baby's skull, and therefore through two
thicknesses of bone. It must be remembered, however, that not only are
the bones of a baby's skull much less thick than those of an adult's
skull, but they are much less densely ossified, and so throw far less of
a shadow.

The dense shadows cast by bone are, at least at present, an insuperable
obstacle to skiagraphing the soft translucent organs of the body which
are enclosed within a more or less complete bony case, as the rays will
be intercepted by the bones. Efforts, therefore, to skiagraph the heart,
the lungs, the liver, and stomach, and all the pelvic organs, probably
will be fruitless to a greater or less extent until our methods are
improved. While a stone in a bladder outside the body would undoubtedly
be perceptible, in the body the bones of the pelvis prevent any
successful picture being taken.

[Illustration: FIGURE 6.--SKIAGRAPH OF A DEAD HAND AND WRIST, SHOWING
TWO BUCK-SHOT AND A NEEDLE EMBEDDED IN THE FLESH.

("American Journal of the Medical Sciences," March, 1896.)]

To turn from the hindrances to the advantages of the application of the
method to the bones, one of the most important uses will be in diseases
and injuries of bones. In many cases it is very difficult to determine,
even under ether, by the most careful manipulations, whether there is a
fracture or a dislocation, or both combined. When any time has elapsed
after the accident, the great swelling which often quickly follows such
injuries still further obscures the diagnosis by manipulation. The X
rays, however, are oblivious, or nearly so, of all swelling, and the
bones can be skiagraphed in the thinner parts of the body at prese