ORIGINAL METHOD OF ARTIFICIAL PARTHENOGENESIS 161 



put directly into hypertonic sea-water (50 c.c. sea-water -f 

 8 c.c. 2J m NaCl). Temperature 18 C. 



The maximum consumption of oxygen was reached in the 

 second hour in which the effect of membrane formation was 

 almost complete. In this case the eggs of a female were used 



TABLE XXXI 



UNFERTILIZED EGGS 



which were obviously very susceptible to this treatment. The 

 effect of the hypertonic solution upon the rate of oxidation in 

 the unfertilized egg was as great as that produced by artificial 

 membrane formation through butyric acid or by fertilization 

 with sperm. 



In many cases the treatment of eggs of S. purpuratus with 

 hypertonic sea-water leads to no membrane formation and no 

 development, or only to the development of a limited number 

 of eggs. Consequently the rise in the rate of oxidation caused 

 in such cases should be smaller than that caused by artificial 

 membrane formation with butyric acid which usually takes 

 effect in practically all the eggs. 



We give in Table XXXII a series of experiments with 

 hypertonic sea-water of various concentrations. It should be 

 remembered that the addition of 4 c.c., or less, 2^ m Ringer to 

 50 c.c. of sea-water was without effect. The oxygen consump- 

 tion was first measured in normal sea-water, then, for the same 

 quantities of eggs, in a hypertonic solution. The table gives 

 the ratio of the oxygen consumption in hypertonic to that 

 in normal sea-water. 



