ii6 Artificial Parthenogenesis 



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possible. ^ The writer has no a priori objection to this 

 suggestion which agrees with eariier observations by 

 Morgan except that it is at present difficult to harmonize 

 it with all the facts. Why should it be possible to 

 replace the treatment with the hypertonic solution by 

 a suspension of the oxidations in the egg for three hours 

 while we know that lack of oxygen suppresses the for- 

 mation of astrospheres in the fertilized eggs? What 

 becomes of the astrospheres if the treatment with the 

 hypertonic solution precedes the membrane formation 

 by a number of hours or a day (which is possible as 

 we shall see), and why do they not induce cell division, 

 if Herlant's idea is correct? Nevertheless the sugges- 

 tion of Herlant deserves to be taken into serious con- 

 sideration. 



6. How can an alteration of the surface of the egg 

 • — e. g.j a cytolytic or other destruction of the cortical 

 layer — lead to a beginning of development? The 

 answer is possibly given in the relation of oxidation to 

 development. The writer found in 1895 that if oxygen 

 is withdrawn from the fertilized sea-urchin egg it can 

 not segment and this seems to be the case for eggs in 

 general.^ In 1906 he found that the rapid disintegra- 

 tion of the egss of the sea urchin which follows artificial 



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^ It Is also important to remember that the formation of astrospheres 

 after mere membrane formation occurs considerably more slowly than 

 if the egg has also received a treatment with a hypertonic solution. 



^ The writer found that the eggs of Fundiiliis will segment a number 

 of times even if all the oxygen has apparently been removed. 



