n6 Artificial Parthenogenesis 



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

 suggestion which agrees with earlier 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., 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 is withdrawn from the fertilized sea-urchin egg it can 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. 2 In 1906 he found that the rapid disintegra- 

 tion of the eggs of the sea urchin which follows artificial 



1 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. 



3 The writer found that the eggs of Fundulus will segment a number 

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



