toneal infection; but when the infection
of the glands constitutes the most prominent sign, the term _tabes
mesenterica_ is sometimes employed. Here the glands, enlarged, form a
doughy mass in the abdomen, leading to marked protrusion of the
abdominal walls, with wasting elsewhere and diarrhoea.

The liver is seldom attacked by tubercle, unless in cases of general
miliary tuberculosis. Now and then it contains large caseous tubercular
masses in its substance.

An important fact with regard to the tubercular processes in the
digestive organs lies in the ready response to treatment shown by many
cases of peritoneal or mesenteric invasion, particularly in the young.

The later sequelae of syphilis display a predilection for the rectum and
the liver, usually leading to the development of a stricture in the
former, to a diffuse hepatitis or the formation of gummata in the
second. In inherited syphilis the temporary teeth usually appear early,
are discoloured and soon crumble away. The permanent teeth may be sound
and healthy, but are often--especially the upper incisors--notched and
stunted, when they are known as "Hutchinson's teeth." As the result both
of syphilis and of tubercle, the tissues of the liver and bowel may
present a peculiar alteration; they become amyloid, or lardaceous, a
condition in which they appear "waxy," are coloured dark mahogany brown
with dilute iodine solutions, and show degenerative changes in the
connective tissue.

The _Bacillus typhosus_ discovered by Eberth is the causal agent of
typhoid fever, and has its chief seat of activity in the small
intestine, more especially in the lower half of the ileum. Attacking the
lymphoid follicles in the mucous membrane, it causes first inflammatory
enlargement, then necrosis and ulceration. The adjacent portions of the
mucous membrane show acute catarrhal changes. Diarrhoea, of a special
"pea-soup" type, may or may not be present; while haemorrhage from the
bowel, if ulcers have formed, is common. As the ulcers frequently extend
down to the peritoneal coat of the bowel, perforation of this membrane
and extravasation into the peritoneal cavity is easily induced by
irritants introduced into or elaborated in the bowel, acting physically
or by the excitation of hyper-peristalsis.

True Asiatic cholera is due to the comma-bacillus or spirillum of
cholera, which is found in the rice-water evacuations, in the contents
of the intestine after death, and in the m