ugh they can promote the healing of the sores in the
late stages. For this reason iodids must always be used in
connection with mercury or salvarsan if the disease itself is to be
influenced. It is occasionally difficult to get patients to
understand this after they have once taken "drops," as the medicine
is often called. Otherwise the use of iodids in syphilis is of
medical rather than general interest.

Chapter VIII

The Treatment of Syphilis (Continued)

SALVARSAN

+The Discovery of Salvarsan ("606").+--Salvarsan, or "606," is a
chemical compound used in the modern treatment of syphilis. It was
announced to the world by Paul Ehrlich, its brilliant discoverer, in
December, 1910. Ehrlich and his Japanese co-worker, Hata, had some years
before been impressed with the remarkable effect certain dyes had on the
parasites infesting certain animals and which resemble the germs that
cause the African sleeping sickness in man. When one of these dyes was
dissolved and injected into the blood of the sick animal, the dye
promptly picked out and killed all the parasites, but did not kill the
animal. Dyes are very complex chemical substances and certain of them
seem to have an affinity for germs. It occurred to Ehrlich that if a
substance could be devised which was poisonous for the germ and not for
the patient it might be possible to prepare a specific for a given
disease, acting as quinin does in malaria. By combining a poison with a
dye it might be made to pick out the germs and leave the body unharmed.

[Illustration: PAUL EHRLICH [1854-1915]

(From "Year Book of Skin and Venereal Diseases," 1916, vol. ix.
"Practical Medicine Series," Year Book Publishers, Chicago.)]

The poison which had already been shown to be especially effective in
killing germs like those of syphilis was arsenic. The problem was to
get arsenic into such a combination with other chemical substances that
it would lose its poisonous quality for man, but still be poisonous for
the spirochete of syphilis. Ehrlich and Hata began to make chemical
compounds of arsenic in the laboratory with chemical substances like the
dyes. As the compounds grew more complex they were tested on animals and
some of them found to have the qualities for which their inventors were
searching. Some of them are even used at the present time in the
treatment of certain diseases. The six hundred and sixth compound in
this series, when