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FORMATION OF HYDROCHLORIC ACID. 477
also, or both, take part in the formation of free acid is disputed. 1
There
can be no doubt that the hydrochloric acid of the gastric juice origin-
ates in the chlorides of the blood, because, as is well known, a secretion
of perfectly typical gastric juice takes place in the stomachs of fasting
animals or those which have starved for some time. As the chlorides
of the blood are derived from the food, it is easily understood, as shown
by Cahn,2
that in dogs after a sufficiently long common-salt starva-
tion, the stomach secreted a gastric juice containing pepsin, but no free
hydrochloric acid. On the administration of soluble chlorides, a gastric
juice containing hydrochloric acid was immediately secreted. The
conditions are not so simple, because in the first case not only does the
amount of hydrochloric acid diminish but, as shown by Wohlgemuth
and then by Kudo, the quantity of juice diminishes greatly, and on the
introduction of NaCl the quantity of juice secreted increases. Accord-
ing to Pugliese 3 the gastric juice in starvation, after a certain time,
has a neutral reaction, and the introduction of NaCl does not now change
its properties. In the secretion of free acid it is assumed by Pugliese
that the gland cells, which decompose the chloride, have sufficient
amounts of protein at their disposal. On the introduction of alkali
iodides or bromides, Kulz, Nencki and Schoumow-Simanowski 4
have
shown that the hydrochloric acid of the gastric juice is replaced by HBr,
and to a less extent by HI. The secretion of free hydrochloric acid
from the alkaline blood has been explained in various ways, but as yet
no satisfactory theory has been suggested.5
In regard to the secretion of pepsin we must recall that this last
is not already produced, but is formed from a preliminary step, a pep-
sinogen or propepsin. Langley 6 has positively shown the existence
of such a substance in the mucous coat. This substance, propepsin,
shows a comparatively strong resistance to dilute alkalies (a soda solu-
1
See Heidenhain, Pfliiger’s Arch., 18 and 19, and Hermann’s Handbuch, 5, part I,
" Absonderungsvorgange;" Klemensiewicz, Wien. Sitzungsber,. 71; Frankel, Pfliiger’s
Arch., 48 and 50; Contejean. 1. c; Kranenburg, Archives Teyler, Ser. II, Haarlem,
1901; and Mosse, Centralbl. f. Physiol., 17, 217; Fitzgerald, Proc. Roy. Soc. B. 82,
83; L6pez-Suarez, Bioch. Zeitschr. 46, 490 (1912).
2
Zeitschr. f. physiol. Chem., 10.
1
Wohlgemuth, Arbeiten aus d. pathol. Institute, Berlin, 1906; Kudo, Bioch.
Zeitschr. 16, 217 (1909), Pugliese, Maly’s Jahresb., 36, 394.
4
Kulz, Zeitschr. f. Biologie, 23; Nencki and Schoumow, Arch, des sciences biol.
de St. Petersboura, 3.
5
Koeppe, Pfliiger’s Arch., 62; Benrath and Sachs, ibid., 109; Maly, see v. Bunge’s
Lehrbuch der physiol. u. pathol. Chem., 4. Aufl., 1898; Schwarz, Hofmeister’s Bei-
trage. 5,
6
SchilT, Lecons, sur la physiol. de la digestion, 1867, 2; Langley and Edkins, Journ.
of Physiol., 7.
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