of the tertiary ulcer,
however, are not always so characteristic as the above description would
imply. It is to be diagnosed from the "leg ulcer," which occurs almost
exclusively on the lower third of the leg; from Bazin's disease (p. 74);
from the ulcers that result from certain forms of malignant disease,
such as rodent cancer, and from those met with in chronic glanders.

_Gummatous Infiltration of the Skin_ ("Syphilitic Lupus").--This is a
lesion, met with chiefly on the face and in the region of the external
genitals, in which the skin becomes infiltrated with granulation tissue
so that it is thickened, raised above the surface, and of a brownish-red
colour. It appears as isolated nodules, which may fuse together; the
epidermis becomes scaly and is shed, giving rise to superficial ulcers
which are usually covered by crusted discharge. The disease tends to
spread, creeping over the skin with a serpiginous, crescentic, or
horse-shoe margin, while the central portion may heal and leave a scar.
From the fact of its healing in the centre while it spreads at the
margin, it may resemble tuberculous disease of the skin. It can usually
be differentiated by observing that the infiltration is on a larger
scale; the progress is much more rapid, involving in the course of
months an area which in the case of tuberculosis would require as many
years; the scars are sounder and are less liable to break down again;
and the disease rapidly yields to anti-syphilitic treatment.

[Illustration: FIG. 41.--Ulceration of nineteen year's duration
in a woman aet. 24, the subject of inherited syphilis, showing active
ulceration, cicatricial contraction, and sabre-blade deformity of
tibiae.]

_Tertiary lesions of mucous membrane and of the submucous cellular
tissue_ are met with chiefly in the tongue, nose, throat, larynx, and
rectum. They originate as gummata or as gummatous infiltrations, which
are liable to break down and lead to the formation of ulcers which may
prove locally destructive, and, in such situations as the larynx, even
dangerous to life. In the tongue the tertiary ulcer may prove the
starting-point of cancer; and in the larynx or rectum the healing of the
ulcer may lead to cicatricial stenosis.

Tertiary lesions of the _bones and joints_, of the _muscles_, and of the
_internal organs_, will be described under these heads. The part played
by syphilis in the production of disease of arteries and of aneurysm
will be referred