THE ACID OF THE GASTRIC JUICE. 359 
lactic acid or other organic acid is formed, which disproves the theory 
that lactic acid is first formed and then decomposes sodium chloride, so 
forming free hydrochloric acid. 1 
It may here be pointed out that experiments have been made by 
Neneki and Schoumova-Simanowsky 2 to ascertain the possibility of 
replacing the chlorine by other halogens, so as to form hydrobromic or 
hvdriodic acids. These experiments were performed on dogs operated 
on by Pawlow's method, 3 and the animals were fed with food in which 
sodium chloride was as far as possible absent. Some had added to their 
f 1 sodium bromide, others sodium iodide. The administration of 
sodium bromide resulted in the animals becoming so ill after a week or 
so that the experiments had to cease. The gastric juice was secreted as 
before, but the hydrochloric acid was largely replaced by hydrobromic 
acid. In the case of those dogs to which sodium iodide was administered, 
though less general disturbance resulted from the administration than 
was the case with sodium bromide, yet the amount of hydriodic acid 
replacing hydrochloric acid was very small. 
Reciprocity between the secretion of hydrochloric acid and the reaction 
of the urine. — That the hydrochloric acid of the gastric juice is formed 
from the chlorides of the blood plasma, is likewise shown by Mary's 4 
observation that at the same period after a meal at which the secretion 
of gastric juice is at a maximum, the acidity of the urine is at a minimum, 
and may be replaced by an alkaline reaction. One function of the kidneys 
is to preserve unaltered in degree the alkalinity of the blood. If now 
neutral salts, such as sodium chloride, be removed from the blood, split 
up in some manner by the agency of the gastric gland cell into hydro- 
chloric acid and sodic hydrate, of which the hydrochloric acid is sent 
towards the stomach cavity, while the alkali is expedited in the opposite 
direction back to the bloocl stream, it follows that the alkalinity of the 
blood will be increased. Hence, to preserve equilibrium, the kidneys 
must excrete a less proportion of acid salts, or, if the rate of increasing 
alkalinity of the blood demands it, must separate an alkaline tiuid from 
the bloocl. This is experimentally found to lie the case. Under ordinary 
circumstances, the kidneys preserve the constant value of the alkalinity 
of the blood, by excreting phosphates of the alkalies so proportioned that 
the reaction is acid, hut during active digestion, 2 to 4- hours after a full 
meal such as dinner, the relative amounts of bases and phosphoric acid 
are so altered that the reaction becomes neutral or faintly alkaline, or, as 
it is often commonly but not very exactly expressed, in the first case 
monosodic phosphate (NaH 2 P0 4 ) is secreted with acid reaction; in the 
second, disodic phosphate NaJIPCh with alkaline reaction. 5 
Theories as to the mode of origin of the hydrochloric acid. — Many 
ingenious theories have been proposed to account for the specific function 
of the gland cells of the stomach, of splitting up such a stable substance 
1 See p. 352. 
- Arch. f. exper. I'>>/]<. n. Pharmacol., Leipzig, 1S94, Bd. xxxiv. S. 313. 
3 See article on " Mechanism of Gastric Secretion." 
4 Ann. d. Chem., Leipzig, 1874, Bd. clxxiii. S. 232. See also Quincke, Jahrcsb. u. d. 
Fortschr. d. Thier-Chem., Wiesbaden, 1874, Bd. iv. S. 241; Stein, ibid., 1876, Bd. vi. 
S. 161. 
5 The reaction will really vary according to the relative amounts of base and acid 
present. Monosodic phosphate alone dissolved in water has an acid reaction, disodic 
phosphate similarly has an alkaline reaction, and mixtures in varying proportions can 
have acid, neutral, "or alkaline reaction. In a complex mixture such as urine, no one can 
say to what the reaction is due, but only that there is an excess of alkali or acid. 
