94 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



indirect effect of the ammonia solution. The latter induces the 

 development in the unfertilized eggs, but if they are not 

 treated with the hypertonic solution they will disintegrate. 



The case is similar to our experience with artificial mem- 

 brane formation by weak acids. The eggs will die after this 

 treatment if they do not receive the necessary second treat- 

 ment. It is not the weak acid which kills the eggs in this 

 case but the membrane formation without the addition of the 

 second factor. If fertilized eggs receive the same treatment 

 with a weak acid they will not suffer at all. 



