The call for oxygen by the heart 83 



(d) The effect of potassium chloride on a feebly beating heart. 



Gas per gram per min. 



Period Oxygen Carbonic acid 



I Before KC1 -030 -061 



II After -027 -048 

 Later -020 -020 



Later . -012 -007 



II 



F IG . 46. Before and after KC1. 



(e) The effect of barium chloride following upon potassium 

 chloride (the same heart as above). 



Oxygen per gram per min. 



Fig. 46. Period II, under influence of KC1 -012 



Fig. 47. Period I, after injection of BaCl 2 -040 



(f) The effect of a further dose of barium chloride which 

 induces contraction. 



Gas per gram per min. 



Period I 



Period II.. 



Oxygen 

 040 

 030 



CO, 

 010 

 013 



FIG. 47. Showing the effect of barium chloride. 



62 



