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. Ina 
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 * e ve 
10:05 100 * “ 
10:06 96 * a se 
10:07 98 * He se 
10:08 90 * x es 
10:11 - 60 “ a ss 
10:12 54. e se 
10:13 be ee se 
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 
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