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492 DIGESTION.
fact has been substantiated by the observations of Paschutin, Brown"
and Heron, Bastianelli, and Tebb.1
A lactose-inverting enzyme,
a lactase, also occurs, as shown by Rohmann and Lappe, Patjtz and
Vogel, Weinland, and Orban,2
in new-born infants and young ani-
mals, and also in grown mammals which were fed upon a milk diet (see
Chapter I, page 52). The lactase can be obtained more abundantly
from the mucosa than from the juice and according to some occurs only
in the cells. The claims as to the occurrence of a glucoside splitting
enzyme are disputed (Frouin, Omi 3
)
.
Besides erepsin and the other enzymes mentioned, the intestinal
mucosa also contains substances which have an inhibitory action upon
pepsin and trypsin. (Danilewsky and Weinland 4
), also enterokinase
or a mother-substance of the same, and finally also the so-called ’pro-
secretin. These two last-mentioned bodies, which are closely connected
with the secretion of pancreatic juice, will be discussed in connection
with this digestive fluid.
The various enzymes are not formed in equal quantities in all parts
of the intestine. Diastase and invertase occur, according to Boldy-
reff, all through the intestine, while the lipase on the contrary does not
occur in the lower parts. The kinase occurs only in the upper part of
the intestine (Boldyreff, Bayliss and Starling, Delezenne). Ac-
cording to Hekma the kinase occurs in all parts of the intestine, but
most abundantly in the duodenum and the upper part of the jejunum.
The enzymes, Falloise claims, generally occur in greatest abundance
in the upper parts of the intestine; but the erepsin occurs to a greater
extent in the jejunum than in the duodenum. According to the investi-
gations of Vernon the behavior of erepsin is not the same in different
animals. In cats and hedge-hogs the duodenum is richer in erepsin than
the jejunum and ileum; in rabbits it is the reverse, namely, the ileum
is much richer than the duodenum. The secretin, according to Bay-
liss and Starling, is formed entirely in the upper part of the intestine..
The epithelium-cells of the glands or the mucous membrane are generally
considered as the seat of formation of the enzymes, and the same is
true also for the enterokinase, according to Bayliss and Starling,.
Paschutin, Centralbl. f. d. med. Wissensch., 1870, 561; Brown and Heron, Annal.
d. Chem. u. Pharm., 204; Bastianelli, Moleschott’s Untersuch, zur Naturlehre, 14
(this contains all the older literature). See also Miura, Zeitschr. f. Biologie, 32; Wid-
dicombe, Journ. of Physiol., 28; Tebb, ibid., 15.
2
Rohmann and Lappe, Ber. d. deutsch, chem. Gessellch., 28; Pautz and Vogel,
Zeitschr. f. Biologie. 32; Weinland, ibid., 38; Orban, Maly’s Jahresber., 29.
3
Frouin and Thomas, Arch, internat. de Physiol., 7; Omi, Das Verhalten dea
Salizins irn tierschen Organisrnus, Inaug.-Dissert. Breslau, 1907.
* See footnote 3, p. 486.
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