The Origin of the Hydrochloric Acid mm the Gastric Tubules.* 
By Mabe. Pureroy FITZGERALD. 
(Communicated by Prof. A. B. Macallum, F.R.S. Received June 4, 1910.) 
(From the Biochemical Laboratory of the University of Toronto.) 
[PLatEes 7—9.] 
In 1823 William Prout? brought forward the view that the acid normally 
existing in the stomach was free hydrochloric acid, or to quote his own 
words, “free or, at least, unsaturated muriatic acid.” This opinion was 
based on the analyses made by him of the gastric contents of the rabbit 
and of other animals, and of the fluid ejected from the human stomach in 
severe cases of dyspepsia. He said further: “ With respect to the nature 
of this acid, very various opinions have been entertained. Some of the 
older chemists seem to have considered it as an acid swi generis; by others 
it was supposed to be the phosphoric, the acetic, the lactic, etc. No less 
various have been the opinions respecting its origin and use, some supposing 
that it is derived from the stomach itself, and is essential to the digestive 
process, others that it is derived from the food, or is a result of fermenta- 
tion, etc.; in short,. there seems to be no physiological subject so 
imperfectly understood, or concerning which there has been such a variety 
of opinions.” 
These words written in retrospection by the first exponent of the free 
hydrochloric acid theory, when read in the twentieth century, have the 
significance also of a prognostication, for during the past eighty-seven years 
interminable discussion has ensued between the advocates of the mineral 
and organic acid theories respectively, and in spite of the efforts of the 
physiologist, biologist, and bio-chemist in their several fields, uncertainty 
still exists on many and similar points. This is true in particular of the 
structure or structures of the gastric mucosa directly concerned with‘ the 
formation and secretion of the hydrochloric acid, as well as of the existence 
even of hydrochloric acid in a demonstrable form within the gland tubules. 
Bickel,t one of the most recent writers on the subject, calls attention to 
* Part of this research was carried out during the tenure of a Travelling Fellowship of 
the Rockefeller Institute for Medical Research, New York, 1908. 
+ W. Prout, ‘ Phil. Trans.,’ 1824, p. 45. 
t A. Bickel, “Magen und Magensaft,” article in ‘Handb. d. Biochemie d, Menschen u. 
Tiere.’ Carl Oppenheimer, 1909, vol. 3, Part 1, p. 72. 
