644 STUDIES IN GENERAL PHYSIOLOGY 



ever, the only light that can be thrown upon the nature of 

 the process of fertilization must be expected from an analysis 

 of the effects of a loss of water upon the egg. 



It seems as if the liquefaction of the nuclear membrane 

 and other constituents of the nucleus were a prerequisite for 

 cell-division. Norman showed that a certain increase in the 

 concentration of the sea-water brings about a distribution of 

 the chromosomes in the egg. Morgan's observations agree 

 with this. But as all these observations were made with 

 solutions whose osmotic pressure was considerably higher 

 than that of the solutions used in my experiments, new ob- 

 servations will be required to decide this question. Hoppe- 

 Seyler, in one of his papers, points out that a loss of water 

 on the part of the protoplasm brings about a diminution 

 in the processes of oxidation. We know that lack of 

 oxygen can bring about the liquefaction of solid con- 

 stituents. I add these remarks for those who enjoy the 

 speculative side of biology. But at the best a theory can- 

 not give us anything more than the facts it includes, and 

 it is therefore clearly our task to supply the lacking ex- 

 perimental data in this field of biology before we begin 

 to theorize. 



7. I think we should try to discover first of all whether 

 the process of development can be started by depriving the 

 egg of water in a few forms only, or whether this is a gen- 

 eral condition. I have thus far tried among the sea-urchins 

 Arbacia and Strongylocentrotus f ranciscanus and purpuratus. 

 Each of these forms is capable of osmotic parthenogenesis. 

 I am confident that the same is true for all species of sea- 

 urchins, although the optimal increase in the osmotic pressure 

 of the surrounding solution may vary for different forms. 

 But I consider it of more importance that with the same 

 methods I have been able to produce artificial partheno- 

 genesis in a starfish (Asterias Forbesii). By putting the 



