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 Eohmann and others in relation bo this question (see p. 108) deserve, 
however, careful consideration. 
2. Changes in the proieid. — 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 oh' is increased. The amount of oxygen 
absorbed from the blood is also raised, but not in proportion ; hence the 
fraction carbo^anhydnde^aled ^ (gee more ^ „ Bespiration ")• 
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, 1815, S. 72; Ranke, "Tetanus, 
Leipzig, 1865; Heidenhain, Arch. f. d. ges. Physiol., Bonn, B<1. iii. S. 574. 
»Griitzner, iMd., Bd. vii. S. 255 : Gscheidlen, ibid., Bd. viii. S. 506. 
1 Sitzungsb. d. h. Akad. d. Wissensch., Wien, Bd. xx. 
5 Ztschr. f. physiol. Chem., Strassburg, Bd. vi. S. 525. 
6 KTttkenberg was unable to obtain myosin ("Weitere Untersuch. zur vergleich. 
Muskelchem." Vergleich. physiol. Studien, 2 Reihe, Abtli. 1, S. 143-7). 
