CHAP. IX.] THE CONTRACTILE TISSUES. 365 



This statement has been contradicted by Nawrocki 1 . Voit has found 

 the creatme to be diminished by activity 2 . 



6. Changes in the proportion of Glycogen and Sugar. 



As was first pointed out by Ranke, during tetanus sugar is 

 produced in muscle. At the same time there is a diminution in the 

 amount of glycogen (Nasse 3 ). It is quite unknown whether the sugar 

 is produced at the expense of the glycogen. 



7. Changes in the amount of Fat and volatile fatty acids during 



activity. 



Ranke 4 thought he had established that the quantity of fat 

 increases in muscle during activity, but the conclusion is probably 

 not warranted by the experimental data 5 . The same remark applies 

 to the statement of Sczelkow 6 that during tetanus there is a 

 diminution of the volatile fatty acids contained in muscle 5 . 



8. Oxidizing and reducing properties of Muscle during rest and 



tetanus. 



Griitzner shewed 7 that whilst resting muscle is able to oxidize 

 pyrogallic acid, muscle which has been tetanized fails to do so. He 

 further shewed that solutions of sulphate of indigo undergo a change 

 of colour when circulating through tetanized muscle, which is of 

 such a kind as to point to the production of reducing substances 7 . 

 Gscheidlen 8 has further shewn that during activity nitrates are con- 

 verted into nitrites. 



B. Changes in the chemical composition of the medium surrounding 



muscle. 



a. When muscle is exposed to the air. 



,_ . The study of 'muscular respiration,' or the study 



1 Respira- rj , , . J , . , 11 



tion' of * the physiological processes of muscle by examining 



muscle : the air to which muscle is exposed, seems to have 



methods of first been systematically practised by George Liebig 9 

 in 1850. His method was the simple one of en- 

 closing the muscles in a tube inverted over a surface 



1 Nawrocki, Centralblatt, 1865, p. 417. 



2 Voit, Zeitschr. f. Biol. iv. 1868 (p. 77). 



3 Nasse, Pfliiger's Archiv, Vol. n. (1869) p. 97. 



4 Eanke, Tetanus, p. 190. 



6 See Hermann's criticism, Untersuchungen uber den Stojfwechsel, &c., p. 86 and 87. 



6 Sczelkow, " Die fliichtigen Fettsauren des Muskels und ihre Veranderung wahrend 

 des Muskeltetanus." Archiv f. Anat. u. Phys. 1864, p. 672. 



7 Griitzner, "Ueber einige chemische Eeactionen der thatigen und unthatigen 

 Muskeln." Pfliiger's Archiv, Vol. vii. (1873) p. 255. 



8 Gscheidlen, "Ueber das Keductionsvermogen des thatigen Muskels." Pfliiger's 

 Archiv, Vol. vin. (1873) p. 506. 



9 Georg Liebig, "Ueber die Eespiration der Muskeln." Archiv fur Anat. Phys. 

 u. wiss. Med. (J. Miiller), 1850, p. 393. The method was first suggested by Du Bois- 

 Beymond. 



