If during the time of contraction, we wished, by mechanical pressure made on the stomach, to make a part of the aliments which it contained pass into the œsophagus, it would be necessary, in order to accomplish it, to employ a very considerable force; and often even we should not succeed. It seems that pressure increases the intensity of the contraction, and prolongs its duration. If, on the contrary, the stomach is pressed during relaxation, it is very easy to make the substances it contains pass into the cavity of the œsophagus. If it be a liquid, the slightest pressure, sometimes even its own weight, or the tendency which the stomach itself has to contract, will bring about this result. When the stomach is laid bare and distended above measure, fluid does not usually enter into the œsophagus, because, as we have said, the distension of the stomach is a cause which prolongs the contraction of the œsophagus. The passage of a fluid in the œsophagus is usually followed by its entrance into the stomach. Sometimes however the fluid is thrown out. When it goes into the stomach, the œsophagus contracts nearly the same as in deglutition, sometimes almost immediately after it has entered it; at other times the œsophagus allows itself to be considerably distended before it pushes it into the stomach. It was at the moment of deglutition that Haller observed the motions of the œsophagus, and the description which he has given of them is very accurate for the two superior thirds of the canal; but the action of the inferior third is essentially different; and this distinction seems to have escaped him. Haller says that the relaxation of each circular fibre immediately follows the contraction; and this is true of the portion of the canal situated in the neck and in the superior part of the thorax; but it is not accurate for the inferior portion, in which we see that the contraction of all the circular fibres is continued long after the entrance of solids or fluids into the stomach. At this moment the mucous membrane of the cardiac extremity of the œsophagus, pushed by the contraction of the circular fibres, forms a very considerable projection into the cavity of the stomach. The contraction usually coincides with the period of inspiration, when the stomach is more strongly compressed; the relaxation takes place most often at the time of expiration. When the aliments have once entered the stomach, it is this contraction of the inferior part of the œsophagus which opposes their return. The resistance that is offered at the other orifice is not of the same species. In living animals, whether the stomach be empty or full, the pylorus is uniformly shut by the contraction of its fibrous ring and the contraction of its circular fibres. There is frequently seen in the stomach another contraction, at one or two inches distance, which