CHAP. IX.] 



THE CONTRACTILE TISSUES. 



357 



and exposed to the vacuum both before and after treatment with 

 phosphoric acid. 



These experiments may be illustrated by the following notes : 



Experiment. Three frogs prepared as above described. Tetanus was 

 induced at intervals during 3| hours 1 . 



MUSCLES IN EEPOSE. WEIGHT 13-4 grms. ( = 12-67 c.cm.). 



MUSCLES TETANIZED. WEIGHT 20-2 grms. (=19-09 c.cm.). 



Whence it appears that in tetanus the carbonic anhydride which 

 a vacuum can extract, added to that which is liberated by acids, may 

 rise as high as 12'08 p. c. by volume of the muscle used. Further, 

 thafc the carbonic anhydride set free by an acid is constant in resting 

 and tetanized muscle. 



Experi- 

 ments of 

 Pfliiger and 

 Stintzing. 



From the experiments of Hermann, which have 

 just been detailed, we may conclude that muscle 

 contains some constituent which in the course of 

 contraction or of rigor suffers a decomposition and 

 yields carbon dioxide in a condition to be removed by the air-pump. 

 Further, that after scalding (p. 352), or after acidification by phos- 

 phoric acid (p. 353), this constituent is no longer capable of decompo- 

 sition by the means which commonly bring rigor about. But although 

 it is then incapable of decomposition by a vacuum at a temperature 

 of 50 C., it appears to yield to tbe prolonged action of boiling water 2 , 

 splitting up with the liberation of carbon dioxide. In the experi- 

 ments in question the muscles of rabbits were used. They were 

 deprived of blood, finely minced, and then plunged into a large 

 volume of briskly boiling water, which was kept boiling for two or 

 three hours. The carbon dioxide which escaped was absorbed, 

 with every precaution to avoid losses, by means of caustic solutions, 

 and afterwards determined both by weighing the potash bulbs and 

 also by the gasometric analysis of the carbonate formed. 



1 Hermann, Op. cit. p. 118. Expt. 14. 



" E. Stintzing, " Untersuchungen u. die Mechanik der physiologischen Kohlen- 

 saurebildung." Pfluger'a Arch.f. d. ges. Physiol. Vol. xvm. 1878, p. 388. 



