104 THE LACTIC ACID GROUP. 



It is not probable that the lactic acid and lactates found in the 

 contents of the stomach and intestines, are entirely derived from 

 the acid of the secreted gastric juice ; indeed it is certain that the 

 greater part of the lactic acid, occurring both there and in the chyle, 

 may be traced to the conversion of the starch or sugar of the 

 food; we should, however, on the other hand, be drawing too 

 general a conclusion, if we assumed that all the starch and all the 

 sugar of the food must be converted into lactic acid, in order that 

 the functions of the organism may be duly fulfilled. In the course 

 of our subsequent physiological considerations, we shall explain the 

 grounds why we cannot accept this view, notwithstanding that it 

 is apparently supported by positive observations. This much is, 

 however, supported by facts, that a portion of these substances is 

 actually converted into lactic acid, and passes into the blood in the 

 form of alkaline lactates. If we adopt Liebig's ingenious division 

 of food, into true food for nutrition and food for the respiration, we 

 know of no substitute which could better act in the blood as food 

 for the respiration than the alkaline lactates, which, as we have 

 seen, undergo rapid combustion in the blood, and are thus converted 

 into carbonated alkali, in a word, nothing could be a better sup- 

 porter of animal heat than the alkaline lactates. 



If the lactic acid in the fluid saturating the muscles, although 

 undoubtedly derived from the effete muscular tissue, be not a 

 pure product of decomposition, there is much in favour of 

 Liebig's* hypothesis, that an electric tension influencing the 

 function of the muscles, is established by the acid muscular juice 

 and the alkaline contents of the capillaries. 



In the urine and sweat, lactic acid occurs only as a product of 

 excretion; for even if, in some cases, it may contribute to the 

 solution of the earthy constituents of the urine, its occasional 

 absence in this fluid shows that other substances effecting that 

 object are also present. 



I formerly regarded lactic acid as one of the most important 

 agents in the solution and transportation of many of the animal sub- 

 stances and earthy salts of the animal organism; but a more 

 thorough insight into the processes of animal chemistry, has led me 

 almost entirely to renounce this view ; for although If have recently 

 convinced myself that the solvent power which lactic acid exerts 

 over basic phosphate of lime, far v exceeds that of acetic acid, and 



* Op. cit, 



t Jahresb. der gee. Med. 1843, 8. 10. 



