CHAP. IX.] THE CONTRACTILE TISSUES. 369 



Then, by (i), 



and (v-p) = nfi + l .................. ...... (iii); 



whence /w, = - -. ........................ (iv). 



This gives the value of //,, which is the distance between two fixed points 

 q and o of the proximal limb of the manometer. 



Having determined /u, carefully, once for all, it is clearly easy to 

 determine the volume of air under observation, diminished as it is by a 

 muscle preparation or any apparatus of unknown volume which may, in 

 an experiment, be introduced into the cylinder. It is only necessary to 

 ascertain the height of mercury which must be poured into the distal 

 limb to raise the proximal surface of mercury from q to o, and apply the 

 formula 



V (the unknown volume) 



By means of this apparatus Valentin was able to confirm Mat- 

 teucci's statements ; but he pointed out that comparable results could 

 only be obtained by employing small preparations and by restricting 

 the experiment to the first half-hour. He found that the relative 

 amount of absorbed oxygen, which Matteucci had discovered to be 

 greater than the exhaled carbonic anhydride, became less during con- 

 traction: that is to say, during contraction more carbonic anhydride 

 is exhaled than oxygen is absorbed. He noticed also that muscles 

 which have been fatigued by prolonged tetanus yield more carbon 

 dioxide and absorb more oxygen absolutely (though less relatively 

 to the carbon dioxide) than sound and vigorous muscles ; and this 

 he thought to be due to an enfeebled power of - resisting the 

 disintegrating action of the atmosphere, owing to some altered consti- 

 tution of the tissue which is characteristic of the state of exhaustion. 



To Valentin, therefore, belongs the credit of pointing out that tbe 

 so-called 'respiration' of muscular tissue is in part a phenomenon of 

 putrefaction ; but it was Hermann who clearly enunciated this fact and 

 perfectly discriminated the living and the dead factors in the process. 



Hermann metn d adopted by Hermann was extremely 



simple 1 : The muscle-preparation was suspended by a 

 platinum wire in a wide absorption tube, which was then inverted over 

 a mercury bath in such a manner that tbe open mouth dipped below 

 the surface, and the mercury stood at the same level outside and inside 

 the tube. The tube thus enclosed an unmeasured volume of air at 



1 Hermann, Stojfwcclisel der Muskeln, p. 32. 



G. 24 



