1910, | Hydrochloric Acid in the Gastric Tubules. 91 
consequence, the free acid diffuses in the opposite direction, that is, out, into 
the inter-tubular tissue. 
The source of the hydrochloric acid in the parietal cells is, without doubt, 
the chlorides, present, as already shown, in greater abundance in them than 
in the chief cells or other adjacent tissue elements. ‘The results of observa- 
tions with Macallum’s cobalt sodium hexanitrite method for demonstrating 
potassium* have not yet shown that the latter element occurs more 
abundantly in the parietal than in the chief cells, consequently the 
chlorine demonstrable in the parietal cells must be associated chiefly, if not 
entirely, with sodium. 
Rosemann+ made analysis of the gastric juice of the dog, and, calculating 
from his results, it was found that in the ash the proportion of the potassium 
to the sodium was 1:1:23 and 1:2°17, whereas in the blood plasma the 
proportion is 1:0°0685. Rosemann consequently concluded that the acid 
arises not through simple diffusion out of the blood, but from the bodies 
of the cells concerned. As the amounts of these elements in the gastric 
juice are very small (K = 0:03077—0:04328, and Na = 0:01979-0:02502), 
and, further, as the percentage of potassium in the juice does not greatly 
exceed that of potassium in the blood plasma (= 0:025 per cent.), it is 
possible that, though the parietal cells take up the two alkaline chlorides 
from the blood plasma and lymph, yet in the formation of the acid they 
utilise only the sodium chloride, the sodium being retained to pass back into 
the blood and lymph. If potassium chloride constituted a source of the 
chlorine of the acid in the gastric juice, the potassium in the latter would 
have, as in the case of sodium, undergone relatively a great diminution in 
amount. 3 
In conclusion, I desire to express my grateful thanks to Prof. A. B. 
Macallum, at whose suggestion this work was undertaken, for his supervision 
and for affording me the facilities for carrying out the research in the Bio- 
Chemical Laboratory of the University of Toronto, and, in particular, I wish 
to acknowledge my indebtedness to him for his valuable help in the chemical 
matters connected with the investigation, and with the physico-chemical 
interpretation of the results. 
* A. B. Macallun, ‘Journ. Physiol., 1905, vol. 32, p. 95. 
t Rosemann, Joc, cat., pp. 522—523. 4 
