120 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



Hence by a treatment with a hypertonic solution for a 

 sufficient length of time unfertilized eggs retain as long as they 

 live the quality of being immune against the disintegration 

 which follows artificial membrane formation. What is the 

 nature of this alteration ? Warburg found that in unfertilized 

 eggs without membranes the rate of oxidation is increased by 

 hypertonic solutions, and we were able to confirm his observa- 

 tion. This suggested the idea that possibly a treatment of such 

 eggs with a hypertonic solution would raise their rate of oxida- 

 tion permanently and that this might be the cause of their 

 immunity against the disintegrating processes following arti- 

 ficial membrane formation. This was a priori not very probable 

 since we found that the corrective effect of the hypertonic solu- 

 tion after artificial membrane formation in the egg of S. pur- 

 puratus is not due to an increase in the rate of oxidations. 



6. We were therefore anxious to see if the rate of oxidation 

 caused by the treatment of unfertilized eggs of S. purpuratus 

 (without membrane formation) was permanently maintained. 

 For this purpose the consumption of oxygen in an unfertilized 

 lot of eggs of S. purpuratus was measured at 18 C. in four suc- 

 cessive periods. 



Oxygen 

 Consumption 

 in 90 Minutes 



In normal sea-water . 30 mgni. 



In hypertonic sea- water (50 c.c. sea- water +9 c.c. 2^ m 



NaCl+KCl+CaCl 2 ) 0.67 mgm. 



In normal sea-water half an hour later 0.51 mgm. 



In normal sea-water twenty-one hours later 0.48 mgm. 



While it is obvious that these eggs continue to show an 

 increased rate of oxidation for at least 22 hours, the rate is 

 very much lower than after fertilization or after the artificial 

 membrane formation. Through the treatment of the eggs in 

 the above-mentioned experiment the rate was increased 2.2 

 times and the next day it had fallen to 1 . 6 times. This 



