EMETICS AND VOMITING 103 



Calves carelessly managed manifest the same disposition to 

 allay their discomfort by eating earthy matters. Antacids 

 given with or just after meals neutralise this gastric and 

 intestinal acidity. After producing local and direct effects 

 on the digestive organs, they undergo absorption, and pro- 

 duce remote antacid effects on the blood and urine. 



GASTRIC TONICS or stimulants, sometimes called stomachics, 

 aid gastric digestion and improve the appetite. Such 

 results occur when, in experiments, the stomach walls are 

 gently irritated, and are also produced by small doses of 

 stimulants and bitters. In certain conditions of gastric 

 irritation, where an excess of a weak, inefficient juice is 

 secreted, stimulants or bitters are, however, unsuitable, and 

 small doses of mineral acids, or of gastric sedatives, such as 

 salts of bismuth, or prussic acid, are prescribed. 



EMETICS are agents which cause vomiting. This is effected 

 by firm compression of the stomach between the diaphragm 

 and the abdominal muscles, and by the simultaneous con- 

 traction of the longitudinal fibres which pass from the 

 oesophagus round the gastric walls. When the stomach is 

 thus compressed from behind, and drawn forward, the 

 familiar spasmodic movements of retching result. When 

 concurrently, however, with these movements, the cardiac 

 orifice is dilated, the contents of the stomach are thrown up, 

 and vomiting occurs. Sir Lauder Brunton thus describes 

 the phenomena of vomiting : ' Uneasiness is felt ; the in- 

 spirations become deeper ; several swallowing movements 

 are made, which sometimes carry down sufficient air to 

 distend the stomach moderately. After several deep in- 

 spirations, there suddenly comes one which is deeper still. 

 Then, instead of this being followed by expiration, the glottis 

 shuts to prevent the escape of air ; the diaphragm again con- 

 tracts still more deeply into the abdomen, and pulling the 

 ribs together, the abdominal muscles forcibly contract ; the 

 left half of the stomach is drawn upwards, and the cul-de-sac 

 flattened out ; the cardiac orifice dilates, and the contents of 

 the stomach are forcibly expelled. The pylorus remains 

 firmly contracted, and allows but little escape into the 

 intestines.' 



The movements of vomiting are modified respiratory and 



