88 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



mixture of 50 c.c. m/2 NaCl+2.5 c.c. m/2 CaCl 2 the fertilized 

 eggs of Arbacia were injured after three hours and ten minutes 

 to such an extent that they were not able to develop after they 

 were transferred to sea-water. All the fertilized eggs of the 

 same female if kept the same length of time in the same solu- 

 tion free from oxygen developed and many reached the pluteus 

 stage. Some of the eggs taken out after seven hours from this 

 solution free from oxygen were still able to develop into larvae. 

 The addition of five drops of a 1/10 of 1 per cent KCN solution 

 to 50 c.c. of the abnormal solution acted just as well if not 

 better than lack of oxygen. (This may have been due to the 

 fact that the solution was slightly alkaline which often acts 

 beneficially in solutions containing Ca.) The same could be 

 shown for analogous solutions in which the CaCl 2 was replaced 

 by MgCl 2 , SrCl 2 , or BaCl 2 . 



In a mixture of 49 c.c. 6/8 m grape sugar +1 c.c. sea-water 

 which was exposed to oxygen the eggs were injured to such an 

 extent after three hours that practically no egg was able to 

 develop when transferred into sea-water. Eggs which had 

 been for three hours in the same solution freed from oxygen 

 were practically all able to develop. 



In this case we were dealing with solutions of substances 

 for which the egg is normally impermeable. It was of consider- 

 able interest to find out whether lack of oxygen has the same 

 life-saving effect if the harmful substance diffuses easily into 

 the egg. For this purpose distilled water and narcotics were 

 selected. Newly fertilized eggs of Arbacia were distributed 

 into the following solutions: 



(1) 27.5 c.c. sea- water +22. 5 c.c. distilled water 



(2) 27.5 c.c. sea- water +22. 5 c.c. distilled water+5 drops 1/10 of 



1 per cent NaCN. 



The eggs in the first solution had suffered in five hours and 

 forty minutes to such an extent that no egg was able to develop 

 into a larva, after they were transferred to sea-water. The 



