39 8 OTTO GLASER. 



INTERPRETATION OF EXPERIMENTS ON PREVENTION OF AUTO- 

 PARTHENOGENESIS. 



Analysis of the means by which a process can be prevented 

 may be even more suggestive than a similar analysis of the means 

 by which it can be induced, and this proves to be true in the 

 present case. How then are these experiments to be understood? 



I. The Block in Washed Eggs. The prevention of fertilization 

 by washing (F. R. Lillie, 'i3 3 ), according to the fertilizin theory, 

 is due to the absence of the intermediary body with which both 

 sperm and egg receptors normally unite. We cannot, however, 

 despite the superficial similarity of the two cases, attribute the 

 auto-parthenogenetic block to the absence of suitable bonds for 

 the egg receptors since the surface film of the ovum is peifectly 

 permeable for fertilizin. This must diffuse into the eggs from which 

 it has been removed the moment they are exposed to the con- 

 centrations employed for initiation. If this is correct, then the 

 prevention of auto-parthenogenesis in washed eggs must be 

 explained in some other way. This however is not necessarily 

 fatal to the fertilizin theory, for these same experiments strongly 

 suggest that a mere increase in permeability is insufficient to 

 initiate development, a suggestion still further reinforced by the 

 second type of block to be considered presently. 



The experiments with washed eggs are also suggestive from 

 another standpoint. Lillie (loc. cit.) tells us: "If it be true that 

 the egg contains its own fertilizing substance it might also be 

 possible to induce parthenogenesis by increasing the concentra- 

 tion of this substance to a certain point. . . ." The washed eggs 

 however demonstrate that the fertilizin experimentally added 

 to the solution about the eggs has no fertilizing effect, and if it 

 has none when the eggs have been washed, there is no good ground 

 for considering its effect different when the eggs have not been 

 washed. " Hetero-parthenogenesis " strongly backs up this 

 position. It appears most likely therefore that in auto-partheno- 

 genesis the fertilizin experimentally added, plays the same role 

 as any other permeability increasing agent effective in the 

 artificial initiation of development. If this is correct, and further- 

 more, if the parthenogenetic block in washed eggs is not identical 

 with the fertilization block brought about by the same means, 



