PHYSIOLOGICAL EFFECTS OF LACK OF OXYGEN 411 



I have repeated this experiment eight limes, always with 

 the same result. It was of importance now to determine 

 whether the number of heart-beats increases, and how much 

 it increases, when a heart which has attained its minimum 

 rate in hydrogen is again exposed to the oxygen of the air. 



In one such experiment the current of 

 hydrogen was turned on at 9:10 A. M. 

 The number of heart-beats was 120 per 

 minute. At 11 the number of heart-beats 

 had fallen to 42, and soon thereafter the 

 minimum of 24 heart-beats was reached. 

 At 2 : 40 the number of heart-beats was 

 still 24. At 2 : 44 the embryo was taken 

 out of the gas-chamber and brought 

 into fresh water, 'and at 2:48 the num- 

 ber of heart-beats was counted; it was 

 then 30. The further 

 course of the experi- 

 ment is shown in the 

 following table: 



10 



1 



90 



SIO 



FIG. 125 



2:48 

 2:49 

 2:50 

 2:55 

 3:00 

 3:03 



40 beats per minute 



60 

 66 

 66 



" 

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