594 MUSCLES. 



According to SIEGFRIED the amount of phosphocarnic acid is dimin- 

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

 intense muscular activity, and the mother-substance of lactic acid can 

 at least in part be phosphocarnic acid. The question as to the forma- 

 tion of lactic acid during activity, and the origin of the phosphocarnic 

 acid is certainly in many points somewhat undecided; the general 

 view seems to be, that during work lactic acid is formed, which transforms 

 a part of the diphosphates into monophosphates. 



The amount of proteins in the removed muscles is, according to the 

 earlier investigators, decreased by work. The correctness of this state- 

 ment is, however, disputed by other investigators. Earlier reports in 

 regard to the nitrogenous extractive bodies of the muscle in rest and 

 in activity are likewise uncertain. According to the recent researches 

 of MoNARi* 2 the total quantity of creatine and creatinine is increased by 

 work, and indeed the amount of creatinine is especially augmented 

 by an excess of muscular activity. The creatinine is formed essentially 

 from the creatine. The investigations of GRAHAM BROWN and CATHCART 

 on removed nerve-muscle preparations of frogs, and those of S. WEBER 3 

 on hearts, indicate an increase in the formation of creatine and creatinine 

 during work. WEBER found that the working heart gave up creatine 

 (and creatinine) to RINGER'S solution, and indeed much more when 

 strongly active than during a lesser activity. An increased creatinine 

 elimination after work does not occur according to several investigators 

 (see Chapter XIV) and according to PEKELHARING and v. HOOGENHTJYZE 

 with ordinary muscle activity neither an increased creatine formation 

 nor an increased creatinine elimination takes place. In the tonic 

 contraction the creatine is formed from the proteins, and correspond- 

 ingly according to PEKELHARING and HARKiNK 4 the creatinine elimina- 

 tion is increased under the influence of the muscle tonus. The purine 

 bases are produced, according to BURIAN, in the muscles themselves, 

 also in activity, and an increased formation takes place during work 

 due to a re-formation. ScAFFiDi 5 found on the contrary, with frogs and 

 tortoise, during work that a diminution of the total quantity of purine 

 bases occurred and indeed not the free but the combined purines. 



Attempts have been made to solve the question relative to the 

 behavior of the nitrogenized constituents of the muscle at rest and during 



1 Siegfried, Zeitschr. f. physiol. Chem., 21; Macleod, ibid., 28. 



2 Maly's Jahresber., 19, 296. 



3 Cathcart and Graham Brown, Journ. of Physiol., 37; Weber, Arch. f. exp. Path, 

 u. Pharm., 58. 



4 Pekelharing and v. Hoogenhuyze, Zeitschr. f. physiol. Chem., 64, with Harkink, 

 ibid., 75. 



5 Burian, Zeitschr. f. physiol. Chem., 43; Scaffidi; Bioch. Zeitschr., 30. 



