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CHYME AND DIGESTION IN THE STOMACH. 479
juice occurs, which gradually mixes with the swallowed food, and digests
it more or less strongly. The material in the stomach during digestion,
which has a pasty or thick consistency, and is called chyme, is not a
homogeneous mixture of the ingesta with the various digestive fluids,
gastric juice, saliva, and gastric mucus, but the conditions seem to
be more complicated.
From the investigations of several workers, 1
on the movements of
the stomach, we conclude that this organ in carnivora and also in man
consists of two physiologically different parts, the pylorus and the
fundus. The greater fundus part, which serves essentially as a reservoir,
may be a rhythmic, strong contraction of the muscle, acting like a
sphincter between it and the pylorus part, be separated from the latter,
and according to some observers so completely so that during contrac-
tion scarcely anything passes from the fundus to the pylorus part.
Differing from the fundus part the pylorus is the seat of very powerful
contractions by which its contents are intimately mixed with gastric
juice and are also driven through the pyloric valve into the intestine.
The contents of the pylorus part have an acid reaction, and a strong
pepsin digestion takes place in the contents, which are thoroughly mixed
with gastric juice. The contents of the fundus, on the contrary, show
a different behavior, for here, as Ellenberger first showed, a special
stratification of the various solid food-stuffs takes place.
By very instructive investigations on different animals (frogs, rats,
rabbits, guinea-pigs, and dogs) Grutzner 2
later showed that when
the aminals are fed with food having different colors, and the stomach
removed after a certain time, and the contents frozen, the frozen sec-
tions show a regular stratification of the contents. These layers are
so arranged that the food first taken is found in direct contact with the
mucosa, while the food taken later is enclosed by that partaken of first,
and this prevents contact with the walls of the stomach. The empty
stomach, whose walls touch each other, is so filled that, as a rule, the
foodstuffs taken later are in the middle of the older food.
Because of this fact only the foodstuffs which lie close to the surface
of the mucous membrane undergo the process of peptic digestion, and
it is principally these ingesta, which lie on the surface and are laden with
pepsin and mixed with gastric juice, which are shoved to the pylorus
end, here mixed and digested, and finally moved into the intestine
1
Hofireister and Schutz, Arch. f. exp. Path. u. Pharm., 20; Moritz. Zeitschr. f.
Biologie, 32; Cannon, Amer. Journ. of Physiol., 1; Sehemiakine, 1. c; Cathcart,
Journ. of Physiol., 1911, 42.
1
See Ellenberger, Pfliiger’a Arch., 114, and Scheunert, ibid., 144; Grutzner, ibid.,
106.
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