358 GASES LIBERATED IN RIGOR AND CONTRACTION. [BOOK I. 



Under these circumstances mammalian muscle yields on prolonged 

 boiling about 100 vols. p. c. (at and 760 mm.) of carbon dioxide. 

 The source of this large volume of gas is not the decomposition of a 

 preexistent compound of it; since, if muscle is well acidified and 

 afterwards washed for many hours at an ice-cold temperature before 

 being boiled, the yield of carbon dioxide on boiling is but little less 

 than when acidification is omitted. There is, in short, little doubt 

 that the constituent of mammalian muscle which liberates carbon 

 dioxide on prolonged boiling, is the same as that which is decomposed 

 in tetanus and rigor; for if muscles are tetanized or made rigid, while 

 at the same time opportunity is offered for the escape of the carbon 

 dioxide which is known to be generated in those processes, the yield 

 of dioxide on subsequent boiling is reduced to a mean of 20 or 30 

 vols. p. c. instead of 100. 



Relation- ^ a com P ar i son be made of the carbon dioxide 



ship between produced during rigor and during tetanus, a very 

 the gases of curious relationship will be found between them, 

 rigid and con- Such a comparison should be made with the limbs of 

 tracting ^ Q same f r0 g . one ji m b being passed into rigor by a 



temporary exposure to 45 C. while still in its skin ; 

 the other limb being tetanized frequently during a long interval. 

 After this preparation each limb should be scalded and otherwise 

 made ready for the extraction of its gases. It will be observed that 

 during the induction of rigor by a temperature of 45 there is an 

 opportunity for the escape of gases, which is however diminished as far 

 as possible by preserving the skin, and making the operation as short 

 as may be. 



After this experiment it will appear that the rigid muscle 

 contains more carbon dioxide than the tetanized. Similar experi- 

 ments further shew that tetanized muscles produce less carbon dioxide 

 on passing into rigor than muscles which have not been tetanized 

 previously. Now, the total carbon dioxide set free by the rigor of 

 muscle which has been tetanized is made up of 



a. the amount in the muscle at the moment of bleeding it ; 



b. the amount produced during tetanus, minus v, the small 

 amount lost to the air in tetanizing ; 



c. the amount produced in rigor, 



while the total carbon dioxide set free by rigor in an untetanized 

 muscle is made up of 



a. the amount in the muscle at the moment of bleeding it ; 



d. the amount produced in rigor. 



But experiment shews that the difference between 



(a + b v + c) and (a + d) 



is about 2 per cent. Hence, if we assume that v = 2 per cent, 

 (and such is not an improbable assumption), then 



(a + b + c) = (a + d), and b + c = d 1 . 



1 Hermann, Op. tit. p. 26. 



