396 STUDIES IN GENERAL PHYSIOLOGY 
posure to a current of hydrogen, were introduced into both 
gas-chambers. I wished to determine whether the renewal of 
segmentation would occur more rapidly and differently in 
pure oxygen than in air. The result was that after fifty 
minutes cleavage occurred almost simultaneously in both 
gas-chambers and in exactly the same way. Cleavage 
occurred only at the periphery and the cells which were 
formed were about the size of those found in the thirty- 
two- or sixty-four-cell 
stage. Ina second experi- 
ment cleavage occurred 
even a little more rapidly 
in the air than in pure oxy- 
gen. For the rest things 
were about the same. 
Under these circumstances 
I saw no reason for con- 
tinuing these experiments ; 
they showedclearlyenough 4 
that it does not —— 
matter, so far B 
as the renewal 
of cleavage of A 
liquefied Cten- [—~—~_} 
olabrus eggs 
is concerned, 
whether air or | ¢ 
pure oxygen is 
FIG. 123 
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