INORGANIC CONSTITUENTS OF MUSCLE. 109 



is that the acid arises from the decomposition of complex molecules, 

 of which proteid forms a part. It is quite possible that the lactic acid 

 may originate in both ways. 



The idea that the acid has a proteid origin was mooted by Kiihne 1 

 in some of his earliest observations. He showed that not only is the 

 acid formed during rigor mortis, but also during the heat-coagulation of 

 myosin. Bohm 2 supported the proteid origin of lactic acid, and his view 

 was endorsed by Hoppe-Seyler. 3 Some of my own experiments showing 

 the development of acid during the coagulation of pure myosin, 4 and 

 Latham's theoretical views 5 on the constitution of the proteid mole- 

 cule, tend in the same direction. Araki 6 found that diminution of 

 oxidation in the body, such as is produced by the inhalation of carbonic 

 oxide, leads to the appearance of lactic acid (and sometimes albumin 

 and sugar) in the urine. This is accompanied by increase in proteid 

 katabolism ; and this again, as Hammarsten 7 points out, is in favour of 

 the same view. 



Inorganic constituents of muscle. The total ash is from 1 to 1'5 

 per cent. In it may be noted the predominance of potash among the 

 oases, and of phosphoric acid among the acids. The following analyses 

 are by Bunge : 8 



In parts per 1000. 



I. II. 



K 2 . . . 4-654 4-160 



Na.,0 . . . 0-770 0-811 



CaO ... 0-086 0-072 



MgO . . . 0-412 0-381 

 Fe 2 3 . . . 0-057 



P 9 5 . . . 4-644 4-58 



Cl ... 0-672 0-70 



S0 3 . . ... 0-10 



More recent work on this question is by J. Katz. 9 The flesh of a 

 large number of animals was investigated. The following figures give the 

 minimum and maximum in 1000 parts of fresh flesh' :K, 2 '4 to 4'6; JN"a, 0'3 

 to 1-5; Fe, 0'04 to 0-25; Ca, 0'02 to 0'39; Mg, 0-18 to 0'37 : P (from 

 phosphates), 1-22 to 2-04 (from lecithin), 0'13 to 0'48 ; (from nuclein), 0'09 to 

 0-32 ; CI, 0-32 to 0-8. 



Chemical changes accompanying the contraction of muscle 



The physiology of muscular contraction, the influence of muscular 

 work in metabolism, the gases of muscle, and other problems, will be 

 studied in other portions of this work. It may not be inappropriate here, 

 however, to conclude this section by stating briefly the main facts, 

 having a chemical bearing, relating to changes accompanying muscular 

 contraction. The changes are in kind similar to those which occur in 



1 ArcJi.f. Anat. u. PhysioL, Leipzig, 1859, S. 795 ; " Myologische Untersuch.," Leipzig, 

 1860, p. 184. 



2 Arch. f. d. ges. PhysioL, Bonn, Bd. xxiii. S. 44. In a later paper (ibid., 1890, Bd. xlvi. 

 S. 265) Bohm reaffirms his position in reference to some criticisms of Werther (ibid., S. 53). 



3 "Physiol. Chem.," S. 666, 667. 



4 Journ. PhysioL, Cambridge and London, 1887, vol. viii. p. 154. These results, how- 

 ever, are criticised by v. Flirth. 



5 Brit. Med. Journ., London, 1886, vol. i. p. 630. 



6 Loc. cit. (Note 11, p. 106). 



7 "PhysioL Chem," 3rd German edition, S. 332. 



8 Ztsclir. f. pliysiol. Chem., Strassburg, Bd. ix. S. 60. 



9 Arch.f. d. yes. PhysioL, Bonn, 1896, Bd. Ixiii. S. 1-85. 



