Vol.LlI March, 1927 No. 3 



BIOLOGICAL BULLETIN 



THE EFFECT OF LACK OF OXYGEN ON 

 SEA URCHIN EGGS. 



ETHEL BROWNE HARVEY. 



It has long been known that fertilized sea urchin eggs may 

 live for some time in the absence of oxygen without division, 

 and divide on readmission of oxygen (Loeb, '95). Since the 

 role of oxygen is of fundamental importance in the life of the 

 cell, I thought it might be of interest to make a study of the 

 changes that take place in individual eggs during lack of oxygen 

 at different stages of development, with special reference to 

 the mitotic figure. The opportunity to procure excellent material 

 for this study was given at the Naples Laboratory, where the 

 perfectly transparent eggs of Echinus microtuberculatus and 

 Strongylocentrotus lividus may be procured during the entire 

 year. It is with great pleasure that I thank Dr. Dohrn for his 

 kindness and courtesy while working in the Stazione Zoologica, 

 and also the Association to aid Seientific Research by Women for 

 the use of their room. 



The observations were made on eggs in a hanging drop in a 

 modified Engelmann's chamber to which pure hydrogen 1 was 

 admitted. The eggs were entangled in threads of platinized 

 asbestos to absorb the last traces of oxygen, and they were 

 stained in methylene blue in order to tell when the oxygen was 

 completely gone. Under the conditions of the experiment, it 

 was found that it took about twenty minutes for the oxygen to 

 be entirely used up as indicated by the colorless condition of 

 the originally blue stained eggs. The eggs of Echinus micro- 

 tuberculatus and Strongylocentrotus lividus gave practically the 



1 The hydrogen was prepared in a Kipp generator from zinc and sulphuric acid 

 washed with alkaline permanganate and passed over platinized asbestos heated to 

 redness in a quartz tube. 



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