gets to the source of trouble. In the old days, while we were
laboriously getting enough mercury into the patient to help him to stop
the invading infection, the germs marched on into his blood and through
his body. With salvarsan, the first dose, given into the blood, reaches
the germs forthwith and destroys them. There is enough of it and to
spare. Twenty-four hours later scarcely a living germ remains. The few
stragglers who escape the fate of the main army are picked up by
subsequent doses of salvarsan and mercury, and a cure is assured. There
is all the difference between stopping a charge with a machine gun and
stopping it with a single-shot rifle, in the relative effectiveness of
salvarsan and mercury at the beginning of a syphilitic infection.

In syphilis affecting the central nervous system, salvarsan,
modified in various ways, may be injected into the spinal canal in
an effort to reach the trouble more directly. The method, which is
known as _intradural therapy_, has had considerable vogue, but a
growing experience with it seems to indicate that it has less value
than was supposed, and is a last resort more often than anything
else. It involves some risk, and is no substitute for efficient
treatment by the more familiar methods. If necessary, a patient can
have the benefit of both.

The _luetin test_ was devised by Noguchi for the presence of
syphilis, and is performed by injecting into the skin an emulsion
of dead germs. A pustule forms if the test is positive. It is of
practical value only in late syphilis, and a negative test is no
proof of the absence of the disease. Positive tests are sometimes
obtained when syphilis is not present. For these reasons the test
is not as valuable as was at first thought.

Chapter IX

The Cure of Syphilis

There are few things about our situation with regard to syphilis that
deserve more urgent attention than questions connected with the cure of
the disease, and few things in which it is harder to get the necessary
cooeperation. On the one hand, syphilis is one of the most curable of
diseases, and on the other, it is one of the most incurable. At the one
extreme we have the situation in our own hands, at our own terms--at the
other, we have a record of disappointing failure. As matters stand now,
we do not cure syphilis. We simply cloak it, gloss it over, keep it
under the surface.