Artificial Parthenogenesis 113 



centration required do not suppress or even lower the 

 oxidations in the egg to any considerable extent, 1 but 

 they prevent the processes of cell division. Hence it 

 seems that the egg disintegrates so rapidly after arti- 

 ficial membrane formation because it is killed by those 

 processes leading to nuclear division or cell division 

 which are induced by the artificial membrane forma- 

 tion. If we suppress these phenomena of development 

 (for not too long a time) we give the egg a chance to 

 recover and if now the impulse to develop is still active 

 we notice a perfectly normal development. If the egg 

 is kept too long without oxygen it suffers for other 

 reasons and cannot develop ; the writer has shown that 

 if eggs fertilized by sperm are kept for too long a time 

 without oxygen they also will no longer be able to 

 develop normally. The short treatment with a hyper- 

 tonic solution supplies the corrective factor required, so 

 that the egg can then undergo cell division at room 

 temperature without disintegrating. 



The correctness of this interpretation, which is in 

 reality mainly a statement of observations, is proved 

 by the two following groups of facts. The older ob- 

 servers had already noticed that the unfertilized eggs 

 of the sea urchin when lying in sea water will die after 

 a day or more, and that occasionally such eggs show 

 nuclear division or even the beginning of cell division 



1 Loeb, J. f and Wasteneys, H., Jour. Biol. Ghent., 1913, xiv., 517; 

 BiocJiem. Ztschr., 1913, Ivi., 295. 

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