1910. | Hydrochloric Acid in the Gastric Tubules. 75 
with negative results. An arbitrary division of the contents of the stomach 
was made, and a portion taken from each of these, viz., from the contents of 
(1) fundus proper, (2) the intermediate region corresponding to the region of 
the cesophageal opening and the lesser curvature immediately adjacent, and 
(3) the pyloric region. 
The production of the Prussian blue reaction was used as the general test, 
and the presence or absence of any one of the three necessary factors determined 
by adding, to a portion of the filtrate, one or both of the others as required. In 
many cases, in addition to this, hematoxylin was employed as a test for iron. 
In the application of the test, a minute quantity of a 1-per-cent. aqueous 
solution of the reagent was added to portions of the filtrates previously 
rendered neutral to litmus paper. As shown by Macallum,* dilute solutions 
of hematoxylin in pure water give a blue-black reaction in the presence 
of “unmasked” iron, but not in the presence of “masked” iron, under 
which category the ferrocyanide and ferricyanide fall. 
The presence of iron was not demonstrated by the hematoxylin method in 
the filtrates of the gastric contents of the dog, nor could the Prussian blue 
reaction be obtained in these. 
In those filtrates pertaining to the rabbit and guinea-pig in which it was 
found possible to produce a Prussian blue reaction, it was generally observed 
that a sufficiency of iron salt already existed, but that potassium ferrocyanide 
had to be supplied or augmented, and, in many cases, the hydrochloric acid 
also. 
In the guinea-pig, the reactions were obtained in one instance only (Guinea- 
pig 3); in this it was found that, although sufficient acid existed for the 
production of the Prussian blue reaction in the filtrates of the different 
portions of the contents removed in the first place—the filtrate of the 
contents of the intermediate region being the most acid—both salts had 
to be added ; and it was found necessary to make a filtrate of the “total ” 
remainder of the contents to obtain sufficient iron for the spontaneous 
occurrence of the reaction on the addition of potassium ferrocyanide, as 
well as for the demonstration of iron by the hematoxylin method. In 
Guinea-pig 2, sufficient acid was present in the filtrate of the fundus and of 
the “total” contents, but the salts were lacking; both the acid and the 
salts were lacking in the filtrates of the contents of the intermediate and 
pyloric regions. 
In the rabbit, the Prussian blue reaction was rarely obtainable in the 
filtrate of the contents of the fundus region proper, but in the case of 
Rabbit 7, in which the solution injected had contained sodium ferrocyanide 
* A. B. Macallum, ‘ Journ. Physiol.,’ 1897, vol. 22, p. 92. 
