and Moore have discovered the spirochaete in the brain in a
number of cases of general paralysis of the insane. The spirochaete may
persist in the body for a long time after infection; its presence has
been demonstrated as long as sixteen years after the original
acquisition of the disease.

In inherited syphilis the spirochaete is present in enormous numbers
throughout all the organs and fluids of the body.

Considerable interest attaches to the observations of Metchnikoff, Roux,
and Neisser, who have succeeded in conveying syphilis to the chimpanzee
and other members of the ape tribe, obtaining primary and secondary
lesions similar to those observed in man, and also containing the
spirochaete. In animals the disease has been transmitted by material from
all kinds of syphilitic lesions, including even the blood in the
secondary and tertiary stages of the disease. The primary lesion is in
the form of an indurated papule, in every respect resembling the
corresponding lesion in man, and associated with enlargement and
induration of the lymph glands. The primary lesion usually appears about
thirty days after inoculation, to be followed, in about half the cases,
by secondary manifestations, which are usually of a mild character; in
no instance has any tertiary lesion been observed. The severity of the
affection amongst apes would appear to be in proportion to the nearness
of the relationship of the animal to the human subject. The eye of the
rabbit is also susceptible to inoculation from syphilitic lesions; the
material in a finely divided state is introduced into the anterior
chamber of the eye.

Attempts to immunise against the disease have so far proved negative,
but Metchnikoff has shown that the inunction of the part inoculated with
an ointment containing 33 per cent. of calomel, within one hour of
infection, suffices to neutralise the virus in man, and up to eighteen
hours in monkeys. He recommends the adoption of this procedure in the
prophylaxis of syphilis.

Noguchi has made an emulsion of dead spirochaetes which he calls
_luetin_, and which gives a specific reaction resembling that of
tuberculin in tuberculosis, a papule or a pustule forming at the site of
the intra-dermal injection. It is said to be most efficacious in the
tertiary and latent forms of syphilis, which are precisely those forms
in which the diagnosis is surrounded with difficulties.

ACQUIRED SYPHILIS

In the vast majority of cases, infec