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THE AMERICAN NATURALIST [Vol. XLIX 



Of these three " corollaries " the first one is the most 

 important, since it claims that the power of the eggs of 

 being fertilized varies with their contents of fertilizin. 

 The proof consisted in this: that eggs were washed a 

 number of times during three consecutive days and after 

 two days the percentage of eggs that could be fertilized 

 were diminished to about one third. 



There is thus the anticipated decrease in the percentage of fertilizations. 



It is a well known fact that the unfertilized eggs of the 

 sea urchin (in fact of all marine animals) perish when 

 they lie for some time in sea water and one of the main 

 causes of this phenomenon is also known, namely oxida- 

 tions. If the oxidations are inhibited through the removal 

 of oxygen or the addition of KCN the life of the eggs can 

 be prolonged. 26 In the mature starfish egg this death 

 which is accelerated by the temperature (and has the high 

 temperature coefficient of many life phenomena) takes 

 place in a few hours, 27 while it begins a little later in the 

 egg of the sea urchin. After the artificial membrane for- 

 mation it takes place very rapidly also in the sea urchin 

 egg (coincident with the enormous increase in the rate of 

 oxidations caused by the artificial membrane formation) 

 and in this case the death of the egg can also be retarded 

 by the withdrawal of oxygen or the addition of cyanide. 28 

 In view of these facts the objection can not be avoided 

 that in Lillie's experiment the number of eggs which could 

 be fertilized fell off after two days to one third not on 

 account of the loss of "fertilizin" but because of the 

 fact that two thirds of the eggs were dead by that time. 

 That this assumption is well grounded is testified by 

 Lillie's own remarks: 



