Nature of Formative Stimulation 137 



in showing that such a solution is only effective in artificial 

 parthenogenesis if it contains free oxygen. If the hypertonic 

 solution is deprived of oxygen it remains without any effect. It 

 remains also inefficient if a trace of KCN is added to it. Since 

 KCN inhibits the oxidations in the cell it is obvious that the 

 hypertonic solution only acts by a modification of the process 

 of oxidation. 



The second method of saving the life of the egg consists in 

 putting it after the membrane formation for about three hours 

 into sea-water which is practically free from oxygen, or contains 

 a trace of KCN whereby the oxidations in the egg are suppressed. 

 If these eggs are transferred after this time into normal sea- 

 water containing free oxygen they are often able to develop 

 normally.^ 



V 



Thus far we have dealt only with artificial parthenogenesis. 

 We are now about to take up the causation of development by 

 a spermatozoon. Is the formative stimulation of the egg by 

 spermatozoon of the same character as that in artificial partheno- 

 genesis? This question can be answered in the affirmative. 

 It is possible to show that the spermatozoon also calls forth the 

 normal development of the egg by at least two substances and 

 that one of these substances acts like butyric acid or saponin 

 in artificial parthenogenesis, inasmuch as it causes the cytolysis 

 of the thin cortical layer of the egg; while the second substance 

 has an effect similar to that of the hypertonic solution. The 

 correctness for this view is proved by the fact that I succeeded 

 in separating these two effects of the spermatozoon. 



If we wish to bring about a separation of these two agencies 

 in the spermatozoon we cannot use the spermatozoa of the 

 same species of sea-urchins from which the egg is taken; for 

 in this case the spermatozoon penetrates at once into the 



1 A further discussion of the facts in this chapter is contained in the next paper 

 on " The Prevention of the Death of the Egg through the Act of Fertilization. " 



