398 



RELATION OF RESPIRATION TO OTHER PROCESSES [CH. XXVII. 



following activity only takes place if the muscle is supplied with 

 oxygen. The output of carbonic acid, in its turn, follows upon the 

 intake of oxygen. The order of events is therefore (1) increase of 

 functional activity, (2) increase of heat formation and oxygen taken 

 in, and (3) increase of carbonic acid put out. 



The following table shows the coefficients of oxidation for resting 

 organs, and the extent to which they are increased in activity. 



In many cases the quantitative relationships have not been 

 worked out. 



Eecent research has shown that in the case of the heart, if N is 

 the number of beats per minute, T, the maximum blood -pressure 

 which is attained at each beat, and 0, the amount of oxygen used : 



NxT 



then is a constant quantity, unless the cardiac muscle is itself 



