564 MUSCLES. 



the quantity of lactic acid in the muscle is diminished in tetanus produced 

 by poison. Contrary to the results of these investigations, MARCUSE and 

 WERTHER have been able to prove the formation of lactic acid during 

 activity; still the reports are discordant. Other observations indicate 

 a formation of lactic acid during activity. Thus SPIRO found an increase 

 in the quantity of lactic acid in the blood during work. COLASANTI 

 and MOSCATELLI found small quantities of lactic acid in human urine 

 after strenuous marches, and WERTHER observed an abundance of lactic 

 acid in the urine of frogs after tetanization. According to HOPPE- 

 SEYLER, on the contrary, in agreement with his view in regard to the 

 formation of lactic acid, it is not produced regularly during work, but 

 only when insufficient oxygen is supplied. ZILLESEN 1 has also found 

 that on artificially cutting off the oxygen from the muscles during life 

 more lactic acid was formed than under normal conditions. 



It is evident that the experiments with the muscles in situ in other 

 words, with muscles through which blood is passing cannot yield any 

 conclusion to the above question, as the lactic acid formed during work 

 may perhaps be removed by the blood. The following objections can be 

 made against those experiments in which lactic acid has been found, after 

 moderate work, in the blood or the urine, as also especially against the 

 experiments with removed active muscles, namely, that in these cases 

 the supply of oxygen to the muscles was not sufficient, and that the lactic 

 acid formed thereby is not, in accordance with the views of HOPPE- 

 SEYLER, a perfectly normal process. Of importance in considering the 

 formation of lactic acid in the muscle and the conflicting opinions on 

 this subject is the work of FLETCHER and HopKiNS. 2 They find that in 

 the preparation of the muscle and its preparation for the investigation 

 for lactic acid several sources of error are possible. Thus mechanical 

 irritation such as warming or treating the muscle with alcohol, which 

 is not ice-cold, brings about the formation of lactic acid. It was also 

 shown that the absence of oxygen is favorable to the formation or 

 accumulation of lactic acid, while abundant oxygen supply acts reversely. 

 The question as to the formation of lactic acid under different physiolog- 

 ical conditions requires further study. 



According to SIEGFRIED the amount of phosphocarnic acid is dimin- 

 ished during activity. MACLEOD claims that this is true only for intense 

 muscular activity, while with ordinary work the organic phosphorus 



1 Astaschewsky, Zeitschr. f. physiol. Chem., 4; Warren, Pfiiiger's Arch., 24; 

 Monari, Maly's Jahresber., 19; Heffter, Arch. f. exp. Path. u. Pharm., 31; Marcuse, 

 1. c.; Werther, Pfliiger's Arch., 46; Spiro, Zeitschr. f. physiol. Chem., 1; Colasanti 

 and Moscatelli, Maly's Jahresber., 17, 212; Hoppe-Seyler, 1. c., and Zeitschr. f. physiol. 

 Chem., 19; Zillesen, ibid., 15. 



2 Journ. of Physiol., 35. 



