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466 DIGESTION. .
refer only to impure gastric juice they are of little value. Rosemann,1
who has investigated the gastric juice secreted by a dog after sham
feeding, found an average of 4.22 p. m. solids, among which 1.32 p. m.
were mineral bodies and about 2.90 p. m. organic substance. The
amount of nitrogen in one case was 0.36 p. m., in another 0.54 p. m. and
the quantity of HC1 was about 5.6 p. m. The ash consisted chiefly of
potassium chloride, namely 980-990 p. m. of the inorganic part. Nencki
and Sieber 2
found 3.06 p. m. solids in the pure gastric juice of a dog.
Nencki 3 found 5 milligrams sulphocyanic acid per liter of gastric juice
of a dog.
In the ash of human gastric juice after sham-feeding Albu 4 found
356.2 p. m. K20; 226.5 p. m. Na20, and 497.3 p. m. CI. The amount
of salts insoluble in water was 23.9 p. m. In hyperacidity he found
almost the same composition.
Besides the free hydrochloric acid, pepsin, rennin, and a lipase are
the other physiologically important constituents of gastric juice.
Pepsin. This enzyme is found, with the exception of certain fishes,
in all vertebrates thus far investigated.
Pepsin occurs in adults and in new-born infants. This condition
is different in new-born animals. While in a few herbivora, such as the
rabbit, pepsin occurs in the mucous coat before birth, this enzyme is
entirely absent at the birth of those carnivora which have thus far been
examined, such as the dog and cat.
In various invertebrates enzymes have also been found which have
a proteolytic action in acid solutions. It has been shown that these
enzymes, nevertheless, are not in all animals identical with ordinary
pepsin. According to Klug and Wr6blewski 5
the pepsins found
in man and various higher animals are somewhat different, an observa-
tion which according to the experience of Hammarsten is very prob-
able. Enzymes also occur in various plants and animal organs, although
not identical with pepsin, but which act in acid reaction. The enzyme
obtained from the Nepenthes, which dissolves proteins only in acid
reaction, stands very close to pepsin. An enzyme more closely related
to ’trypsin or erepsin (see sections III and IV) is, on the contrary,
Glaessner’s pseudopepsin, which according to him is the only peptic
enzyme in the pyloric end. Pseudopepsin, whose existence is disputed
by Klug, while others (Reach, Pekelharing) affirm its occurrence in
1
Pfliiger’s Arch., 118.
2
Zeitschr. f. physiol. Chem., 32.
3
Ber. d. d. Chem. Gesellsch., 28.
4
Zeitschr. f. Path. u. Therap., 5.
6
Klug. Pfliiger’s Arch. 60; Wr6blewski, Zeitschr. f. physiol. Chem., 21.
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