576 DIGESTION. 



the larger afflux of blood; and the different secretions appear to take 

 place in greater abundance; become mixed with the food, and exert an 

 active and important part in the changes it experiences in the stomach. 

 Direct experiment has proved that such augmented secretion actually 

 occurs. If an animal be kept fasting for some time, and then be made 

 to swallow dry food, or even stones, and be deprived of liquid aliment, 

 the substances swallowed will be found, on killing it some time after- 

 wards, surrounded by a considerable quantity of fluid. Such is not 

 the case with animals killed after fasting. The stomach then contains 

 no fluid matter. The augmented secretion in the former case must, 

 therefore, be owing to the presence of dry food in the stomach. That 

 it is not simply the fluid passed down by deglutition, the salivary and 

 mucous secretions, for example, is proved by the fact, that the same 

 thing occurs when the oesophagus has been tied. Besides, if the sto- 

 mach of a living animal be opened, and any stimulating substance be 

 applied to its inner surface, a secretion is seen to issue in considerable 

 quantity at the points of contact ; and, again, if an animal be made to 

 swallow small pieces of sponge, attached to a thread hanging out of the 

 mouth, by means of which they can be withdrawn, they become filled 

 with the fluids secreted by the stomach, and, on withdrawing them, a 

 sufficient quantity can be obtained -for analysis. Such experiments 

 have been repeatedly performed by MM. Reaumur, 1 Spallanzani, 2 and 

 others. In Dr. Beaumont's case 3 the collection of gastric secretion was 

 obtained by inserting an elastic gum tube through the opening: in a 

 short time fluid enough was secreted to flow through the tube. This 

 admixture with the fluids of the mucous membrane of the stomach, and 

 the secretions continually sent down from the mouth by the efforts of 

 deglutition, is the only apparent change witnessed for some time after 

 the reception of solid food. Sooner or later, according to circum- 

 stances, .the pyloric portion of the organ contracts sending into the 

 splenic portion the food it contains: to the contraction dilatation suc- 

 ceeds ; and this alternation of movements goes on during the whole of 

 digestion. After this time chyme only is found in the pyloric portion 

 mixed with a small quantity of unaltered food. This motion of con- 

 traction and relaxation has been called peristole; and it appears, at 

 first, to be limited to the pyloric portion, but gradually extends to the 

 body and splenic portion, so that, ultimately, the whole stomach parti- 

 cipates in it. It consists in an alternate contraction and relaxation of 

 the circular fibres; and the gentle oscillation, thus produced, not only 

 facilitates the admixture of the food with the gastric secretions, but 

 continually exposes fresh portions to their action. The experiments of 

 Bichat satisfied him, that the peristole is more marked, the greater the 

 fulness of the stomach. He made dogs swallow forced-meat balls, in 

 the centre of which he placed cartilage, and found, that when the sto- 

 mach was greatly charged, the cartilages were pressed out of the balls. 

 This did not happen, when the organ contained a smaller quantity of 

 food. 



1 Memoir, de 1'Acad. pour 1752. 2 Exper. sur la Digestion, Geneve, 1783. 



3 Experiments, &c., on the Gastric Juice, p. 106. 



