Nature of Formative Stimulation 137 



in showiag 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 stimidation of the egg by 

 spermatozoon of the same character as that in artificial partheno- 

 genesis? This question can be answered in the aflormative. 

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

 normal development of the egg by at least two sub^'tances and 

 that one of these substances acts Hke 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 



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

 on " The Prevention of the Death of the Egg ttirough the Act of FertiUzation. " 



