ARTIFICIAL PARTHENOGENESIS AND OXIDATIONS 115 



superficial cytolysis or a cytolysis of the cortical layer of the 

 egg. It is obviously this cytolysis and no subsequent morpho- 

 logical change in the egg which causes the increase in the rate 

 of oxidation. We can cause complete cytolysis of the eggs of 

 the sea-urchin by adding a trace of saponin to the sea-water. 

 Wasteneys and I measured the rate of oxidations in a lot of 

 unfertilized eggs in sea-water and found that they consumed 

 0. 15 mg. O 2 per hour at 15 C. Then the eggs were cytolyzed 

 with saponin and the amount of oxygen consumed in one hour 

 at 15 C. was measured again. It was 1 .07 mg. The cytolysis 

 of the eggs increased the rate of oxidation 700 per cent, as much 

 as, or possibly a trifle more than, fertilization. In a similar 

 experiment in which dilute sea-water was used for cytolysis and 

 in which not all the eggs cytolyzed, the rate of oxidation was 

 increased 2.74 times after the cytolysis. The cytolyzed eggs 

 are no longer able to undergo any development or structural 

 change. It is therefore obvious that the increase in the rate 

 of oxidation after membrane formation as well as after fertiliza- 

 tion is due to the mere cytolysis. How the cytolysis can bring 

 about such a result is unknown. 



2. The greatest interest was attached to the question as to 

 how the hypertonic solution affected the oxidations in the eggs 

 after membrane formation. It was found that the eggs in 

 which the artificial membrane formation had been induced 

 with butyric acid consumed oxygen in the hypertonic solution 

 at the same rate as in normal sea-water. 



Some of the eggs of the last-mentioned experiments were 

 also used to compare the rate of oxidation in such eggs in normal 

 sea-water and in hypertonic sea-water (50 c.c. sea-water +8 c.c. 

 2J m NaCl+KCl+CaCl 2 ). 



Oxygen consumption of unfertilized eggs after artificial 

 membrane formation 



In normal sea- water . 85 mg. 



In hypertonic sea-water . 88 mg. 



