394 E - E - JUST. 



tion. This is true, as Schiicking found. Toluene, etc., should 

 likewise be effective, and they are (cf. Herbst). But surely one 

 could scarcely insist upon this same explanation for the effect of 

 the hypertonic sea-water employed in the experiments here re- 

 ported. 



Moreover, in the eggs both of Arbacia and of Echinarachnius 

 any competent observer can see that membrane separation follow- 

 ing insemination is no mere surface tension effect, but an active 

 progressive dissolution of cortical material. In the egg of Echina- 

 rachnius one can actually observe the cortex going into solution; 

 in the egg of Arbacia pigment escapes at this time. If, therefore, 

 we experiment with agents that induce membrane separation, in 

 order to solve the problem of the cortical changes in normal fer- 

 tilization ; despite the fact that such agents do lower the surface 

 tension of the sea-water, we are not justified in the light of the 

 observed phenomena in normal fertilization to postulate any theory 

 at variance with these observed phenomena. Such postulates must 

 cease to have any scientific value. 



To be sure, it may well be that the membranes induced by these 

 agents are not at all comparable to those induced by sperm. Nor, 

 indeed, does it follow that membranes induced by hypertonic sea- 

 water are like those induced by sperm. The main point, however, 

 is something more than this. Hypertonic sea-water, which cer- 

 tainly is not of lower surface tension than normal sea-water, does 

 call forth membranes while the eggs are in the solution. If we 

 must adhere to the surface tension hypothesis, then we must con- 

 clude that the effect of hypertonic sea-water is an exception as is 

 the effect of the sperm in calling forth membrane separation by a 

 cortical breakdown which follows in a wave beginning at the 

 entrance point of the sperm. 



2. Again, the experiments here reported are at variance with 

 the notion that the separation of the membrane is due to a super- 

 ficial cytolysis. 



As I understand it, the term cytolysis connotes a cellular dis- 

 integration. One certainly can not use the term in its strict 

 etymological sense particularly since that misnomer " superficial 

 .cytolysis" has now become widely current. Unfortunately many 

 zoologists use the terms cytolysis and plasmolysis interchangeably. 



