530 SPECIAL PHYSIOLOGY. 



but as to the nature of that acid, they differ widely, some contending 

 that it is organic^ others mineral ; some that it is acetic, lactic, or bu- 

 tyric, others that it is hydrochloric acid, or the acid biphosphate of lime. 

 The latter theory, advanced by Blondlot, has been disproved by Dumas, 

 Bernard, and Melsens, who have shown that not only the carbonate, 

 but also the basic phosphate of lime are soluble in gastric juice, as are 

 also zinc and iron with the evolution of hydrogen gas, properties 

 which a solution of acid phosphate of lime does not possess. 



Dr. Prout, in 1824. Dr. Dunglison, in 1833-34, and Braconnot, in 

 1835, state that they obtained evidences of free hydrochloric acid in 

 gastric juice, the first in the stomach of rabbits killed while digesting, 

 the second in the fluid obtained by Dr. Beaumont from St. Martin, 

 and the last in gastric juice obtained by sponging the stomachs of ani- 

 mals. More recently, Bernard and Barreswill, Pelouze and Thomp- 

 son, have been led to believe, from their own experimental researches, 

 that lactic acid is the agent upon which the characteristic reaction of 

 the gastric juice depends, and attribute the presence of hydrochloric 

 acid in the free state to the decomposition of the alkaline chlorides by 

 the lactic acid at a high heat. Hence, supposing lactic acid to be pres- 

 ent in the fluid of digestion, with chloride of sodium, the fluid which 

 passes over by distillation will, at first, be destitute of hydrochloric 

 acid; but as the liquid becomes more concentrated, and the temperature 

 rises, hydrochloric acid will pass over. Lehmann denies the power of 

 (hydrochloric?) acid to decompose the chloride of sodium, but asserts 

 that chloride of calcium is decomposed by lactic acid, even in vacuo; 

 and hence it is not surprising that pure gastric juice should develop 

 vapors in vacuo, which, when passed into a solution of nitrate of silver, 

 should form chloride of silver. 



Still more recently, Messrs. Bidder and Schmidt declare, as the re- 

 sult of eighteen corresponding analyses, "that pure gastric juice of 

 carnivora, after eighteen to twenty hours' fasting, contained free hydro- 

 chloric acid only, without a trace of lactic or any other organic acid ; 

 while the gastric juice of herbivora contains, with free hydrochloric 

 acid, small quantities of lactic acid, which may, however, be referred 

 to their more amylaceous food." Grunewald's experiments led him 

 to the conclusion that the acid was an organic one, while Schroeder 

 maintains that the fluid obtained by irritating the stomach by peas, 

 owed its reaction to hydrochloric acid. 



With a view of determining this question, the series of experiments 

 referred to were instituted, and conducted in the most careful mariner, 

 and as a result, the following conclusions were arrived at, though some 

 of them were at variance with the doctrines maintained by the writer 

 for many years previous. 



1st. That the secretions of the stomach, when digesting, are in- 

 variably acid. 



2d. That the acid reaction was not due to phosphoric acid. 



3d. That if hydrochloric acid was present, it was in very small 

 quantities. 



4th. That the main agent in producing the characteristic reaction 

 was lactic acid. (Philad. Med. Examiner, July & Sept., 1856 ; Jour, 

 de Physiologic, Jan., 1858.) F. G. S.] 



