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498 DIGESTION.
The way in which the trypsinogen is converted into trypsin is still
unknown and is the subject of dispute. According to one view, proposed
by Pawlow and defended by Bayliss and Starling, the trypsinogen
is transformed into trypsin by the action of the kinase. In the opinion
of Delezenne, Dastre, and Stassano, and others, 1
the trypsin, on the
contrary, is a combination of the kinase and trypsinogen, analogous to
the cytotoxines, which, according to Ehrlich’s side-chain theory, are
combinations between a complement and an amboceptor. (See page
69.)
The specific excitants for the secretion of pancreatic juice are,
according to Pawlow and his collaborators, acids of various kinds-
hydrochloric acid as well as lactic acid—and fats, the latter acting
probably by virtue of the soaps produced therefrom. Alkalies and
alkali carbonates have, on the contrary, a retarding action. It appears
that the acids act by irritating the mucosa of the duodenum. Accord-
ing to London and Schwarz the secretion can also be excited from the
entire jejunum and the upper part of the ileum. The secretion becomes
weaker the further away the exciting source is from the duodenum.2
Water, which causes a secretion of acid gastric juice, likewise becomes,
indirectly, a stimulant for the pancreatic secretion, but may also be
an independent exciter. The psychical moment may, at least in the
first place, have an indirect action (secretion of acid gastric juice),
and the food seems otherwise to have an action on pancreatic secretion
by its action on the secretion of gastric juice.
The most important excitant for the secretion of juice is hydrochloric
acid, but opinions are not in unison as to the manner in which the acid
acts. Pawlow’s school claims that the acid acts reflexly upon the
intestine, causing a secretion of juice. That a reflex action is here pro-
duced is not contradicted by the investigations of Popielski, Wert-
heimer and Lepage, Fleig,3
and others. According to the researches
of Bayliss and Starling, which have been confirmed by Camus, Gley,
Fleig, Herzen, Delezenne, and others, a second factor must also be
active here. Bayliss and Starling have shown that a body which
they have called secretin can be extracted from the intestinal mucosa
by a hydrochloric-acid solution of 4 p. m., and this when introduced into
the blood produces a secretion of pancreatic juice, bile, and in the
opinion of some investigators also of saliva and intestinal juice. The
1
Bayliss and Starling, Journ. of Physiol., 30 and 32, which also cities the other
investigators and also O. Cohnheim, Bioch. Centralbl. 1, 169 and S. Rosenberg, ibid.,
2, 708.
* Zeitschr. f. physiol. Chem. 68, 346 (1910) which also contains the literature.
’ Fleig, Centralbl. f. Physiol., 16, 681, and Compt. rend. soc. biol., 55. See also
footnote 1.
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