THE MECHANISM OF THE VOMITING INDUCED BY ANTIMONY AND POTASSIUM TARTRATE (TARTAR EMETIC).

1. It has been shown that tartar emetic acts on the stomach to induce emesis after its oral administration, that only traces are present in the vomitus following its intravenous injection (Kleimann and Simonowitsch), and that it does not induce emesis when it is applied directly to the vomiting center (Thumas). 2. In the present study, which was made with cats except when otherwise specifically stated, the intravenous injection of tartar emetic caused emesis (typical vomiting movements) after the removal of the entire gastrointestinal tract from the esophagus to the anus. 3. Cutting the vagi inhibits emesis after the intravenous injection of any dose of tartar emetic, though nausea may be induced. 4. Cutting the vagi and simultaneously extirpating the stellate ganglia inhibits both nausea and vomiting after the intravenous injection of tartar emetic. 5. Extirpation of the celiac ganglion and simultaneous cutting of the vagi just below the level of the diaphragm does not prevent emesis following the intravenous injection of tartar emetic. 6. Cutting the vagi prevents vomiting after the introduction of large doses of tartar emetic into the stomach, but massive doses may still cause emesis. Vagotomy probably has less influence on the emetic action of a moderately large dose of tartar emetic introduced into a loop of the duodenum. 7. Atropine has very nearly the same effect on the emetic action of tartar emetic as cutting the vagi, but much larger doses are necessary to abolish the effect of the introduction of tartar emetic into the stomach in moderate amounts than that of equal amounts injected intravenously. 8. The facts just stated point to the heart as the seat of reflex vomiting following the intravenous injection of tartar emetic. 9. The intravenous injection of tartar emetic induces afferent emetic impulses which pass from the heart to the vomiting center mainly by way of the vagus, to a much less extent by way of the sympathetic nerve and the stellate ganglia. 10. The introduction of tartar emetic into the stomach induces afferent emetic impulses which pass upward mainly by way of the vagus, to a much less extent by way of the sympathetic nerve. 11. The introduction of tartar emetic into the duodenum induces afferent emetic impulses which pass upward partly by way of the sympathetic nerve, partly by way of the vagus. 12. It seems probable that the path taken by afferent emetic impulses induced in the gastrointestinal tract by tartar emetic depends on the innervation of the organ concerned, and not on any selective action of the poison on the afferent nerve.