ac sphincter of the stomach
to relax; reversed oesophageal peristalsis causing regurgitation. A
similar reversed action serves in merycism, or rumination, occasionally
found in man, to raise part of the food, lately ingested, from the
stomach to the mouth. Vomiting also is aided by reversed peristaltic
action, both of the stomach and the oesophagus, with the help of the
diaphragm and the muscles of the anterior abdominal wall. Emesis may be
caused both by local nervous influence, and through the central nervous
mechanism either reflexly or from the direct action of substances
circulating in the blood. Further, the causal agent acting on the
central nervous apparatus may be organic or functional, as well as
medicinal. Vomiting without any apparent cause suggests nervous lesions,
organic or reflex. The obstinate vomiting of pregnancy is a case in
point. Here the primary cause proceeds reflexly from the pelvis. In
females the pelvic organs are often the true source of emesis.
Haematemesis accompanies gastric ulcer, cancer, chronic congestion with
haemorrhagic erosion, congestion of the liver, or may follow violent
acts of vomiting. In cases of ulcer the blood is usually bright and in
considerable amount; in cancer, darker, like coffee-grounds; and in
cases of erosion, in smaller quantity and of bright colour. The reaction
of the stomach contents, if the cause be doubtful, yields valuable aid
towards a diagnosis. Of increased acidity in gastric ulcer, normal in
hepatic congestion, it is diminished in cancer; but as the acid present
in cancer is largely lactic, analysis of the gastric contents must often
be a _sine qua non_, because hyperacidity from lactic may obscure
hypoacidity of hydrochloric acid.

Flatulence usually results from fermentative processes in the stomach
and bowel, as the outcome of bacterial activity. A different form of
flatulence is common in neurotic individuals: in such the gas evolved
consists simply in carbonic acid liberated from the blood, and its
evolution is generally characterized by rapid development and by lack of
all fermentative signs.

_The Liver._--The liver is an organ frequently libelled for the
delinquencies of other organs, and regarded as a common source of ill.
In catarrhal jaundice it is in most cases the bowel that is at fault,
the liver acting properly, but unable to get rid of all the bile
produced. The liver suffers, however, from several diseases of its own.
Its fibrous or co