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 -f 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, aiicf 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, has 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 therinochemical 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 in the gastric 



1 " Traite analytique de la digestion," Nancy et Paris, 1843 ; Jahresb. u. d. Fortschr. 

 d. ges. Med., Eiiangen, 1851, Bd. i. S. 97 ; 1858, Bd. i. S. 37. See also Ralfe, Lancet, 

 London, 1874, vol. ii. p. 29. 



2 "Vorlesungen," Wicn, 1885, Aufl. 4, Th. 1, S. 307. 



3 Jdkrcsb. u. d. Fortschr. d. ges. Med., Erlangen, 1862, Bd. i. S. 110. 



4 Arch.f. d. ges. Physiol., Bonn, 1876, Bd. xii. S. 332. 5 See p. 357. 



