736 STUDIES IN GENERAL PHYSIOLOGY 
contained many bacteria. Even after three days, when the 
water was exceedingly foul and cloudy, a portion of the eggs 
which had lain in a heap, that is to say, without oxygen, 
were immature and living. They were introduced into fresh 
water and spread out intoathin layer. They maturated and 
developed into swimming larve upon the addition of sperm. 
It is self-evident of course that even immature eggs finally 
become the prey of bacteria, and so go to pieces in the sea- 
water. 
The same experiment can be made in a somewhat more 
complicated way with pure oxygen and hydrogen. The 
freshly laid eggs of a starfish were distributed into two 
series of eight flasks. The one series of flasks was connected 
with a hydrogen generator; the other with a tank contain- 
ing pure oxygen. Before the beginning of the experiment 
all the air in one of the series of flasks was driven out by 
the current of hydrogen. During the course of the experi- 
ment a vigorous current of hydrogen was maintained. Both 
series of flasks contained freshly laid immature eggs of 
Asterias. The experiment lasted three days, and from time 
to time a flask was removed and its contents examined. The 
eggs which had been exposed to the current of oxygen 
maturated just as rapidly and as numerously as those in ordi- 
nary sea-water, and the mature eggs soon died. In the cur- 
rent of hydrogen maturation did not occur in the majority of 
the eggs, and these remained alive. In the hydrogen 
cultures a rapid development of bacteria occurred, while in 
the oxygen cultures this occurred to a small degree.' 
Treatment with acids which, as we have shown above, 
prevents the maturation of the eggs (without killing them) 
also prevents their death and disintegration. 
Eggs which, without having been in contact with pure 
1Care must be taken in these experiments tbat the air is thoroughly removed 
from the sea-water in the hydrogen flasks before the eggs are introduced into them. 
Of course the hydrogen apparatus must also be free from air. 
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