XV 



THE ACTIVATION OF THE UNFERTILIZED EGG BY BASES 



1. The writer found in 1907 that strong bases are able to 

 cause the unfertilized egg to develop, but that in sonic 

 respects their effect differs from that of acids. While only a 

 short treatment with acid suffices to induce membrane forma- 

 tion and while this action is not prevented by KCN, the strong 

 bases must act on the egg a comparatively long time before 

 they can cause it to develop. And, moreover, their effect is 

 prevented by lack of oxygen or by the presence of KCN. 1 



Like the acids, the bases cause development through a 

 modification of the surface of the egg, but in the case of bases 

 the resulting membrane is as a rule only a fine gelatinous layer, 

 such as is formed through the influence of fatty acids in the egg 

 of Arbacia, although occasionally a typical fertilization mem- 

 brane is formed. The bases act therefore in one respect like 

 the acids, inasmuch as both call forth a typical or atypical 

 membrane formation and this membrane formation is the essen- 

 tial part of artificial parthenogenesis. In order to cause the 

 unfertilized eggs of Arbacia to develop by bases, the following 

 procedure was found to be effective. The eggs of Arbacia 

 are put into 50 c.c. m/2 (NaCl+KCl+CaCl 2 )+0.3 c.c. N/10 

 NH 4 OH for twenty-five minutes, at a temperature of about 22 C. 

 From here they are transferred directly to a neutral hypertonic 

 solution, 50 c.c. m/2 Ringer +8 c.c. 2J m Ringer, for fifteen 

 minutes, and then they are put back into normal sea-water. 

 In this case a large number of eggs develop into larvae, many 

 of which are perfectly normal. It will be found that only 

 those eggs develop into larvae which form the gelatinous film- 



1 Loeb, "Ueber die allgemeinen Methoden der kiiustlichen Parthenogene.se," 

 Pfliiyers Archiv, CXVIII, 572, 1907. 



147 



