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EXPERIMENTS ON DIGESTION. 
The Peristaltic Motion of the Stomach. 
The living stomach, distended by the mass of aliment introduced 
into it in the process of deglutition, reacts upon it by the contraction 
of its muscular tunic. The food, as much by its volume and its 
weight as by its chemical properties, produces a stimulating effect 
on the stomach, and causes it to contract. Walseus, Wepfer, 
Peyer, Sproegel, Schlichting, Schulz, Felix, Haller, Spallanzani, 
and others, have observed the motion of the stomach in animals 
opened when alive, as dogs, cats, pigs, &c. We have uniformly 
observed it more or less distinctly in the animals on which we have 
experimented. 
The motion is in general vermicular, very slow, and often 
scarcely perceptible. It is this which has caused so much doubt 
upon the subject in the minds of some physiologists. The con- 
traction is not simultaneous in the whole extent of the stomach ; — 
it is always partial, so that while one part of the stomach is slightly 
contracted, another is dilated — and when the second is contracted, 
the former is dilated. The portions in which the contractions are 
taking place are thicker, and more rugous. The alternate con- 
tractions and expansions not only take place across the stomach, 
but along it, with reference to the direction of the muscular fibres. 
During the greater part of the time, the movements, which are 
undulatory, are in a direction from the oesophagus towards the 
pylorus, and from the pylorus towards the oesophagus. We 
have sometimes seen the contractions commence at the two ex- 
tremities of the stomach, and unite at the middle of it. The 
strongest and the most sudden contractions are in the neighbourhood 
of the pyloric orifice, where also the muscular coat is thicker than 
any where else. The degree of the contraction of this membrane, 
and the quickness of the various motions, appeared to depend on 
the stimulation produced on the stomach by the food. In dogs and 
cats, that had been fed on bones, bread, flesh, fibrine, and the white 
of eggs coagulated by boiling, the movements of the stomach were 
strongest and most active. 
The consequence of these successive contractions of the muscular 
membrane was that the aliment moved slowly through the cavity 
of the stomach, and that the portions which were dissolved were 
pushed on towards the pylorus. They escaped through this open- 
ing in small quantities during the expansion of the circular fibres 
which guarded it, and thus passed into the duodenum. The peri- 
staltic motion of the stomach continued until the food was com- 
pletely dissolved by the gastric juice, and it had entirely passed, 
although little by little, into the duodenum, through the pylorus. 
