402 STUDIES IN GENERAL PHYSIOLOGY 
or whether the altered metabolism in the initial lack of 
oxygen does not at first lead to a slight acceleration of 
cleavage. Ifthe latter were correct, it would give a basis 
for the explanation of a very purposeful arrangement in 
organic nature, namely, the increase in respiratory activity 
in the lack of oxygen. For if lack of oxygen leads to such 
a universal change in metabolism that more energy is at first 
set free than under normal conditions, then the purposeful 
arrangement of the respiratory center is only a special case 
of a general property of protoplasm. 
Yet the acceleration of cleavage in the Engelmann 
chamber might also be dependent upon an increase in 
temperature. One source of this increase in temperature 
might be sought in these experiments in the heat produced 
in developing hydrogen from zine and sulphuric acid. 
The gas was passed through four wash-bottles before reach- 
ing the gas-chamber, yet it might nevertheless have caused 
an increase in the temperature in the gas-chamber. To 
render this impossible or less possible the gas generator was 
packed in a vessel with ice before beginning the experiment. 
From this the hydrogen was led through a bottle filled 
with chipped ice which was in turn again packed in ice. 
The first three wash-bottles were also kept on ice. The 
temperature of the last wash-bottle through which the 
gas passed before reaching the gas-chamber was carefully 
watched before and during the experiment. No increase 
in temperature was noted when the hydrogen was passed 
through it. 
The same water was used for the eggs in the gas-chamber 
that was used for the control eggs. Every decrease in the 
temperature of the latter through evaporation of the water 
was carefully avoided, and their temperature carefully 
watched. 
Cleavage in the eggs kept in the gas-chamber neverthe- 
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