LACTIC ACID. 107 



of a body in a state of decomposition or transformation, 

 which has been called diastase, effects the solution of 

 the starch, that is, its conversion into sugar; so, a 

 product of the metamorphosis of the substance of the 

 stomach, being itself in a state of metamorphosis which 

 s completed in the stomach, effects the dissolution of 

 all such parts of the food as are capable of assuming a 

 soluble form. In certain diseases, there are produced 

 from the starch, sugar, &c., of the food, lactic acid 

 and mucilage. (24) These are the very same products 

 which we can produce out of sugar by means of mem- 

 brane in a state of decomposition out of the body ; but 

 in a normal state of health, no lactic acid is formed in 

 the stomach. \ 



11. The property possessed by many substances, 

 such as starch and the varieties of sugar, by contact 

 with animal substances in a state of decomposition, to 

 pass into lactic acid, has induced physiologists, without 

 further inquiry, to assume the fact of the production of 

 lactic acid during digestion ; and the power which this 

 acid has of dissolving phosphate of lime has led them 

 to ascribe to it the character of a general solvent. But 

 neither Prout nor Braconnot could detect lactic acid in 

 the gastric juice ; and even Lehmann (see his " Lehr- 

 buch der Physiologischen Chemie," Tom. L p. 285) 

 obtained from the gastric juice of a cat only microscopic 

 crystals, which he took for lactate of zinc, although 

 their chemical character could not be ascertained. The 

 presence of free muriatic acid in the gastric juice, first 

 observed by Prout, has been confirmed by all those 



