I injected into the vein of a dog four grains of an emetic dissolved in two ounces of common water, (in this way vomiting is produced quicker and more certainly;) I afterwards made an opening in the abdomen, and when the first efforts of vomiting began, I quickly drew out the whole of the stomach, which did not prevent the efforts of vomiting from continuing. The animal made precisely the same efforts as if he had vomited; but nothing came from the stomach; this organ remained completely immoveable. I wished then to see what would be the effect of pressure made on the stomach; for this purpose, I placed my right hand on the anterior face of this organ, and my left hand on the posterior face. The pressure was hardly commenced when the efforts of vomiting, that is to say, the contraction of the diaphragm and the abdominal muscles powerfully recommenced. I suspended the pressure; the abdominal muscles and diaphragm soon suspended their contractions. I renewed the pressure; the contractions of the muscles began again; then I suspended it; they ceased; and seven or eight times in succession. The last time, I made a strong and continued pressure; this produced a real vomiting. A part of the substances contained in the stomach was thrown off. I repeated this experiment on another dog; I observed the same facts; only I remarked moreover that the contractions of the diaphragm and the abdominal muscles can be produced by merely drawing by the œsophagus. In the experiment just related, the emetic substance was introduced into the veins, and we have already remarked, that the effects were quicker and more certain than if the same substance had been introduced into the stomach. This alone should make us suspect that vomiting is not owing, as is generally believed, to the impression of the emetic on the mucous membrane of the stomach; for, in this case, its action ought to have been more prompt when it was placed directly in contact with this membrane, than when it arrived at it with the blood after having passed through the lungs and the four cavities of the heart. For the purpose of elucidating this question and of seeing if the contractions of the muscles were the result of the impression produced on the stomach, or if they were excited more directly by the emetic substance mixed with the blood, I made the following experiment: