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, KC1, CaCl 2 , 

 and MgCl 2 (in the proportion in which these salts are present 



TABLE X 



TIME OF EXPOSURE OF THE 

 EGGS TO HYPERTONIC 



SEA-WATER 



PERCENTAGE OF THE EGGS 

 THAT DEVELOPED INTO 



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

 2J 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 



Amount of Alkali Added to the Neutral Hypertonic 



" ~~ 



