108 Artificial Parthenogenesis and Fertilization 



5. It appeared interesting to determine in what way an 

 Increase of the concentration of HO ions in the hypertonic solu- 

 tion would increase the rapidity of its action. To this end 

 not sea-water, but a neutral mixture of m/2 NaCl,.KCl, CaCla, 

 and MgCla (in the proportion in which these salts are present 



TABLE X 



in sea-water) was used. To each 50 c.c. of this solution, 8 c.c. of 

 2| m NaCl solution, also neutral, were added to produce the 

 necessary hypertonicity; then, 0, 0.1, 0.2, 0.4, 0.8, and 1.6 

 c.c. of N/50 NaOH were added each to 50 c.c. of this mixture. 

 The eggs of a S. purpuratus were divided among these solutions 

 after membrane formation had been produced by the use of 

 butyric acid. Table XI gives the percentage of larvae resulting. 



TABLE XI 



Time of Exposure to the 

 Hypertonic Solution 



Amount of Alliali Added to the Neutral Hypertonic 

 Solution in c.c. of N/50 NaHO 



0.1 



0.2 



0.4 



0.8 



1.6 



30 minutes 



40 minutes 

 50 minutes 

 60 minutes 

 70 minutes 







5% 

 20 

 25 

 80 



a few 

 larvae 



10% 



80 



90 



90 



5% 



20 

 50 

 90 

 90 



5% 



20 

 80 

 90 

 90 



a few 

 larvae 



50% 



80 



90 



90 



a few 

 larvae 



20% 

 100 



90 



90 



