Origin of the Hydrochloric Acid in the Gastric Tubules. 57 
this uncertainty, and says an answer is still required to the following 
questions :—“ Wird die Salzséure in den Belegzellen oder iiberhaupt in 
Zellen der Magenschleimhaut selbst gebildet, oder scheiden die Zellen nur 
das Ausgangsmaterial ab, aus dem die Salzsaure im Ausfiihrungsgang der 
Driisen oder an der Oberflache der Schleimhaut entsteht ?” 
The investigation, of which the present communication is the outcome, was 
undertaken (1908-9) with the hope of advancing, by means of micro- 
chemistry, the knowledge requisite to the solution of such questions. Before 
entering into details, an account must be given of some of the work of earlier 
investigators, which in the limits of the present paper must be confined 
mainly to researches definitely directed towards tracing the acid to its seat 
of formation by micro-chemical methods. Respecting the nature of the 
acid, the brief statement must suffice, that the tendency of recent researches 
has been to show that organic acids are only adventitiously present, and the 
view held to-day is that the hydrochloric acid is not entirely free. 
In 1846 Frerichs* held the opinion that the gastric juice was secreted in 
an acid condition, and the free acid present was not of external origin. 
He pointed out that the acid nature of the secretion could be proved, even 
if the fluid found in the stomach was neutral in reaction, for, if in such 
cases the mucosa were scraped, the contents of the deepest part of the 
glands (“ Labdriisen”’) would be found to be acid in reaction. He also states 
that this fact is easily proved in the stomach (“ Vormagen”) of a bird, such 
as the goose, for in the deepest part of the glands a material is found which 
colours litmus red. 
Claude Bernard (1850)t+ was the first to apply micro-chemistry to determine 
the precise seat of formation of the acid of the gastric juice. In his well- 
known Prussian blue experiment the hypothesis was that, since the presence 
of an acid was necessary to the formation of Prussian blue from the inter- 
action of lactate of iron and potassium ferrocyanide, solutions of such salts, 
owing to the alkalinity of the blood, could be introduced into the circulation 
of an animal without fear of their interaction, and that a precipitation of 
Prussian blue would occur when the two salts came into contact with an 
acid fluid or tissue of the body; therefore, if acid were formed in any of the 
glandules of the gastric mucosa its presence would thus be revealed. 
He injected consecutively into the jugular vein of a semi-fasting rabbit a 
solution of lactate of iron and a solution of potassium ferrocyanide, both 
solutions being tepid. Three-quarters of an hour later the animal was killed, 
* F. Th. Frerichs, ‘ Wagner’s Handwiorterb. d. Physiol.,’ vol. 3, Part 1, p. 780. 
t C. Bernard, ‘ Lecons sur les Propriétés physiologiques et les Altérations pathologiques 
des Liquides de l’Organisme,’ Paris, 1859. | 
