406 STUDIES IN GENERAL PHYSIOLOGY 



it again stood still, after which the heart beat rhythmically 

 for one minute (38 beats in a minute), when it again ceased. 

 A few irregular pulsations followed, and then everything 

 was over. Sixteen minutes after turning on the current of 

 hydrogen the heart had come to a complete standstill, but 

 the embryo itself still moved at this time, and even five 

 minutes after the heart and the circulation had ceased 

 entirely the embryo still moved! 



In a third experiment the current of hydrogen was turned 

 on at 11:26 A. M. The number of beats was 90 per minute; 

 in the following minute it was 81, and in the third minute 

 the heart came to a sudden and permanent standstill. In a 

 fourth experiment the current of hydrogen was started at 

 10:03 A. M. The number of heart-beats was 100 per minute. 

 The following table indicates the course of the experiment: 



10:03 100 beats per minute 



10:04 102 " 



10:05 100 " 



10:06 96 " 



10:07 98 " 



10:08 90 " 



10:11 60 " 



10:12 54 " 



10:13 54 " 



The heart then came to a sudden standstill. Three min- 

 utes later the heart again beat twice ; shortly after this it beat 

 regularly for one minute (39 times per minute). The heart 

 then again stopped; a few scattered beats followed, and at 

 10:25 A. M. the heart came to a permanent standstill. 



When the embryos whose hearts had come to a standstill 

 were returned, after not too long a time, to water containing 

 oxygen, resuscitation of the heart followed, and this the 

 earlier, the shorter the time the embryo had remained in the 

 atmosphere free from oxygen. If the eggs remained for one 

 to one and a half hours in the gas-chamber, they became 



