394 



STUDIES IN GENERAL PHYSIOLOGY 



boid pseudopodia. A few minutes later all of the cells sent 

 out such pseudopodia, which soon became shorter, however, 

 as if the substance of the pseudopodia had been torn, c. #., 

 through an emulsion (Fig. 120). The outlines of the germ 



then again became smooth, but not 

 entirely so (Fig. 121), and finally the 

 blastoderm gradually disappeared (Fig. 

 122). The entire series of changes 

 shown in Figs. 118-22 took about forty- 

 five minutes. Besides these changes, 

 another series 

 took place in 



FIG. 118 the blasto _ 



derm and the yolk, which, however, 

 I am not as yet able to interpret^ 

 and which I therefore do not de- 

 scribe, as their description would 

 take up much room without at 



present being of 

 any use. 



If eggs in an 

 advanced state 



of division are introduced into CO 2 , 

 a solution of the cleavage-cells occurs 

 at the periphery just as in hydrogen. 



VII. THE EFFECT OF PURE OXYGEN 

 UPON CLEAVAGE 



In embryological literature one 

 at times encounters the statement 

 that the processes of development in 

 pure oxygen at atmospheric pressure go on differently from 

 those in air. Demoor also states that nuclear division is 

 accelerated in pure oxygen. 



Now, it is one of the established facts of physiology that 



FIG. 119 



