360 CHEMISTRY OF THE DIGESTIVE PROCESSES. 
as sodium chloride, of forming such a strong acid as hydrochloric acid is 
in the face of the alkalinity of the blood, and of determining an alkaline 
stream towards the blood and an acid stream towards the lumen of the 
gland. 
The oldest theory was, that the process was an electrolytic one. 
Blondlot 1 supposed that by electric agency sodium chloride in the 
stomach wall was broken up into sodic hydrate and hydrochloric acid 
(in the language of to-day, hydrolysed, NaCl + H 2 = NaHO + HC1). 
The free acid then, for the most part, acted on the calcium phosphate 
of the blood, forming acid phosphate and a trace of phosphoric acid, 
while a trace of hydrochloric acid also remained free. To such a mixture 
of acid substances (mainly acid calcium phosphate) he ascribed the 
acidity of gastric juice. He electrolysed tricalcic phosphate, suspended 
in a solution of sodium chloride, and claimed to have obtained such 
products as his theory demands. Briicke 2 considered that the energy 
required came from transformation of nervous energy, modified to this 
purpose, and, admitting that the details are not explicable, compared the 
effect to others called forth by nerve impulses, such as the electric effects 
in the electric end-organ of some fishes. He also considered the secretion 
of acid more analogous to electrolysis than to any other known process. 
Lussana 3 supposed that in the glands of the stomach a decomposition of 
the salts of the plasma took place, and that the preponderating part of 
the free acid of the gastric juice was hydrochloric, simply because by far 
the greater part of the salts of the plasma are chlorides. He tried to 
test his theory by intravenous injection of salts not present in quantity 
in blood plasma, such as sulphates and phosphates. He did not, 
however, obtain the corresponding acids in the gastric juice, except 
in the case of borax and tartar emetic, after injection of which traces 
of boric and tartaric acids respectively were found in the gastric juice. 
Buchheim 4 suggested that the chlorides of the plasma combined 
with the proteid, so that the metal combined with one proteid molecule 
and the acid radicle with another ; the latter combination being absorbed 
by the acid-secreting cells and broken up there into proteid and acid. 
These older theories can at best be only regarded as mere specu- 
lations; there is absolutely no experimental proof of them. Nor can 
we lay claim at the present day to a complete knowledge of the 
process of secretion of hydrochloric acid. Only thus far the progress 
of physical chemistry, and a more exact knowledge of the laws of 
solutions, lias brought us, that we no longer need look upon the 
production of hydrochloric acid by the animal organism as a chemical 
wonder. The secretion of hydrochloric acid is still a mystery as great 
as the secretion of pepsin or any other product of cell activity, but 
no greater. 
To the chemist, before the thermochemical work of Thomsen, and 
the diffusion experiments of Maly already described, 5 and when he was 
acquainted with no other means of setting free hydrochloric acid from 
its salts than the electric current or displacement by a stronger acid 
such as sulphuric acid, the occurrence of hydrochloric acid hi the gastric 
1 " Traite analytique de la digestion," Nancy et Paris, 1843; Jahresb. ii. d. Fortschr. 
d. ges. Med., Erlangen, 1851, Bd. i. S. 97 ; 1858, Bd. i. S. 37. See also Ralfe, Lancet. 
London, 1874, vol. ii. p. 29. 
2 "Vorlesnngen," Wien, 1885, Anfl. i, Th. 1, S. 307. 
3 Jahresb. ii. d. Fortschr. d. ges. Med., Erlangen, 1802, Bd. i. S. 110. 
4 Jrch.f. d. ges. Physiol., Bonn, 1876, Bd. xii. S. 332. 5 See p. 357. 
