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. 
