384 INFLUENCE OF MUSCULAR CONTRACTION ON RESPIRATION. [BOOK I. 



the N" of the inspired air (estimated by the method of difference) from the 

 N of the expired air ; a + sign indicates that the N of the expired is 

 greater than that of the inspired. It is evident that all experimental 

 errors, i.e. errors in reading off measurements, etc., will sum themselves 

 algebraically to the 1ST so determined. 



The duration of the experiments was recorded on a revolving cylinder ; 

 and the gases were analysed by Bunsen's method. 



The amounts of CO 2 and O, reduced to the standard temperature and 

 pressure, are averaged per minute of the experiment. 

 II = repose : T = tetanus. 



Cause of A simple consideration of tbe amount of carbon 



the increase dioxide excreted, serves to shew that the increase during 

 of co 2 excre- tetanus is not due simply to favoured elimination. 

 A very large rabbit rarely weighs more than 2 kilogs., 

 of which T V, or 105*23 grms., may be considered to be the weight of the 

 blood. Taking 30 vols. per cent, as the proportion of carbon dioxide 

 in it, this weight of blood includes about 31'6 c.c. of carbon dioxide 

 the total carbon dioxide in the blood of a very large rabbit at a given 

 moment. Now, even if we make the large assumption that the 

 carbon dioxide of the blood is, by rapid elimination, reduced to 

 one half in the course of an experiment, we shall still be quite unable 

 to account for the extraordinary excretion of carbon dioxide in 

 tetanus ; for if this enormous reduction were supposed to be effected 



during a short experiment like Exp. ii., of the above Table, it would 



(01 .(* \ 

 or -i- 5*1 ) of carbon dioxide 



per minute a quantity far less than the observed. Hence the excess 

 of carbon dioxide excreted by the lungs during tetanus must be due 

 to an increased production of it within the body. 



What part of this production has its seat in the tetanized limbs, 

 and what part in the rest of the body, these experiments fail to 

 discover. It is more than probable that the material exchanges of the 

 body at large do not preserve their equilibrium during the manifold 



