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. In a second experi- 

 ment cleavage occurred 

 even a little more rapidly 

 in the air than in pure oxy- 

 gen. For the rest things 

 were aboiit the same. 

 Under these circumstances 

 I saw no reason for con- 

 tinuing these experiments; 

 they showed clearly enough 

 that it does not 

 matter, so far 

 as the renewal 

 of cleavage of 

 liquefied Cten- 

 olabrus eggs 

 is concerned, 

 whether air or 

 pure oxygen is 





FIG. 123 



