no THE CHEMISTRY OF THE TISSUES AND ORGANS. 



muscles during so-called rest; there is an exaggeration of the normal 

 " chemical tone " of the tissue, and an explosive liberation of energy. 



1. Change in reaction. The muscle becomes acid ; this is generally 

 believed to be due to the production of sarcolactic acid. The views 

 of Bohmann and others in relation to this question (see p. 108) deserve, 

 however, careful consideration. 



2. Changes in the proteid. There is no marked and immediate 

 increase of urea in muscular activity, though recent work tends to show 

 that proteid katabolism is increased, and that the increase in urea 

 leaves the body the next day or the day after. The main work, 

 however, appears to fall on the non-nitrogenous part of the muscle, as 

 evidenced by the immediate and large increase in the amount of 

 carbonic anhydride that leaves the muscle. Hermann's theory of 

 muscular contraction assumes that* the change is similar in kind to that 

 which occurs on death, though less in degree. On death, he assumes 

 that the hypothetical molecule he terms inogen l is split into carbonic 

 anhydride, sarcolactic acid, and myosin. But anything like the 

 formation of a clot of myosin has never been observed in living con- 

 tracting muscle. 



3. Changes in the extractives. During tetanus the extractives 

 soluble in water decrease, and those soluble in alcohol increase. 2 

 This appears to be chiefly explicable by the disappearance of glycogen, 

 and appearance of sugar and lactic acid. 



4. Changes in the gases. Hermann's theory just referred to was 

 largely the outcome of his failure to discover oxygen among the gases 

 of muscle. The oxygen used in the formation of carbonic anhydride 

 must therefore be held in complex union within the muscle. On 

 contraction, as on the occurrence of rigor mortis, the amount of 

 carbonic anhydride given off is increased. The amount of oxygen 

 absorbed from the blood is also raised, but not in proportion ; hence the 

 fraction -^^^^i riges . (See more Mly ,. Eespiration >y 



5. Production of reducing substances. Eesting muscle oxidises 

 pyrogallic acid ; tetanised muscle does not. A solution of nitrites 

 passed through contracting muscle is changed into one of nitrates, and 

 the colour of solutions of indigo sulphate is altered in the same 

 way as by reducing agents. 3 A. Schmidt 4 arrived at the same 

 conclusion from the examination of the venous blood of tetanised 

 muscle, but what the reducing substances are that are produced is 

 quite unknown. 



Electrical organs. From the torpedo organ, Weyl 5 extracted, 

 probably from the mucous fluid between the plates, a " torpedo mucin." 

 This, however, yields no reducing sugar. A small quantity of gelatin 

 and a globulin (coagulated by heat at 55- 60) were also obtained. 6 

 The tissue, like muscle, becomes acid and less transparent after 



1 The nearest approach to Hermann's theoretical substance, inogen, is Siegfried's phospho- 

 carnic acid (see p. 103). 



2 Helmholtz, Arch. f. Anat. u. PhysioL, Leipzig, 1845, S. 72; Ranke, "Tetanus," 

 Leipzig, 1865; Heidenhain, Arch. f. d. ges. PhysioL, Bonn, Bd. iii. S. 574. 



Griitzner, ibid., Bd. vii. S. 255 ; Gscheidlen, ibid., Bd. viii. S. 506. 



4 Sitzungsb. d. Tc. Alcad. d. Wissensch., Wien, Bd. xx. 



5 Ztschr. f. physiol. Chem., Strassburg, Bd. vi. S. 525. 



6 Kriikenberg was unable to obtain myosin ("Weitere Untersuch. zur vergleich. 

 Muskelchem." Vergleich. physiol. Studien, 2 Reihe, Abth. 1, S. 143-7). 



