Prolongation of the Life of the Egg 87 



In order to indicate the greater resistance of the unferti- 

 lized eggs the following experiments may be mentioned. Un- 

 fertilized eggs of purpuratus were distributed into the following 

 two solutions : 



(1) 50 CO. 0.54 m NaCl+1.1 c.c. m/2 KCl+1.0 c.c. N/10 NaOH 



(2) 50 c.c. 0, 54 m NaCI-hl . 1 c.c. in/2 KCl+1 .0 c.c. N/10 NaOH-f- 



0.5 c.c. 1/10 of 1 per cent KCN. 



The eggs kept in solution (1) were disintegrated in about six 

 hours. The eggs of solution (2) were still alive after forty-one 

 hours and could still be fertilized after they were transferred 

 into normal sea-water.' (In such experiments the eggs should 

 not be fertilized immediately after they are transferred, but 

 several hours later.) 



It could be shown that lack of oxygen acts like the addi- 

 tion of KCN.^ The unfertilized eggs resist a concentration of 

 NaOH five times as great as that used for the fertilized eggs. 

 This experiment also shows that if the oxidations are retarded 

 in the egg by the addition of KCN it is able to resist the NaOH 

 much longer. 



But it may be doubtful whether we can account in this 

 way for the entire difference between the sensitiveness of ferti- 

 lized and unfertilized eggs. We must possibly take into con- 

 sideration the fact that while the fertilized egg is in direct 

 contact with the alkali, the unfertilized egg is surrounded by 

 two shells, the chorion and the cortical layer. The cytoplasm 

 of the unfertilized egg is therefore in all probability not exposed 

 to the same concentration of NaOH to which the fertilized egg 

 is, which has lost these two layers. 



3. The writer was able to show generally that in many 

 abnormal solutions in which the unfertilized egg lives longer 

 than the fertilized egg, the life of the latter may be prolonged 

 by lack of oxygen or by the suppression of oxidations. In a 



• Loeb, "Ueber die Hemmung der Giftwirkung der Hydroxylioneu aul das 

 Seeigelei mittels Cyankalium," Biochem. Zeitschr., XXVI, 279, 1910. 

 ! Loeb, ibid., 289. 



