METABOLISM IN DISEASES OF BONES AND JOINTS 753 



Mommsen state that they found this acid in the urine in osteomalacia. 

 These investigators extracted with ether, boiled the ethereal ex- 

 tract with zinc oxid, and, observing rhombic crystals in the dried residue, 

 diagnosed them as zinc lactate. They were not justified in so doing; a 

 number of aromatic acids, whose zinc salts may be confounded with zinc 

 lactate hippuric acid, for example may be extracted with ether. By 

 the same method, in fact, Langendorff and Mommsen found lactic acid 

 in normal urine. Neither Schmuzinger, Heuss, nor McCrudden(e) was 

 able to find any lactic acid in the urine in their cases. There is, then, 

 no good evidence that lactic acid occurs in the urine in osteomalacia. 



Lactic acid has been administered to animals in the attempt to in- 

 duce osteomalacia artificially. Only Siedamgrotsky and Hofmeister, 

 who fed large amounts of lactic acid to goats, allege any action on the 

 bones. But they obtained no such effect after administration of the much 

 stronger hydrochloric and sulphuric acids, so that if there were any change 

 in the bones in these experiments, the changes were not improbably 

 due to digestive or other disturbances resulting from the large amounts 

 of lactic acid ingested, and not from acid action. Indeed, it requires con- 

 centrated lactic acid to decalcify bone in vitro, and it was such acid that 

 Moers and Muck and Henning used to demonstrate that lactic acid 

 will decalcify bone; yet no one can suppose that concentrated lactic 

 acid appears in the tissues. As a matter of fact, according to von 

 Mosetig-Moorhof, even fairly concentrated lactic acid does not de- 

 calcify bone; and Heiss, who administered to dogs from two to 

 eight grams lactic acid per day for nearly a year, was unable to observe 

 any effect whatever on the macroscopic or microscopic appearance, or 

 the chemical composition of the bones. Gayet and Bonnet admin- 

 istered one gram lactic acid per day for six months to a female rabbit, 

 who gave birth to a litter of three young during the period. The young, 

 likewise, received lactic acid during the whole period of growth. Neither 

 mother nor young ever showed any evidence of bone disease. More recent 

 experiments (Givens, also Givens and Mendel) have demonstrated that 

 the administration of neither base nor acid has any significant effect on 

 the balance of calcium or magnesium in the body. 



A decreased alkalinity of the blood in osteomalacia (by the old titration 

 method) is alleged by Eenzi, von Jaksch(<;), Issmer, Truzzi, and Eisen- 

 hardt. Fehling(&) and von Limbeck (a) found no such decrease in blood 

 alkalinity; and Senator(gr) found even an increased alkalinity. The 

 alleged decrease in blood alkalinity found by Truzzi persisted even after 

 the patient was cured. As a matter of fact, even a decrease in the alka- 

 linity of the blood or tissue fluids would not make them a better solvent 

 for calcium phosphate ; the presence of free acid is necessary. Free acid 

 cannot occur in the blood stream during life ; any abnormal acid formed 

 in the metabolism would be immediately neutralized, just as the carbonic 



