ARTIFICIAL PARTHENOGENESIS 587 



neutral hypertonic solution, 50 cc. in/2 (NaCl + KCl + 

 CaCy+S cc. 2i m (NaCl + KCl + CaCU. Part of the 

 eggs were transferred after fifteen, twenty-five and thirty- 

 three minutes to normal sea water. Of the eggs that remained 

 only fifteen minutes in the hypertonic solution all perished. 

 About 50 per cent of those that had been in the hypertonic 

 solution twenty-five minutes developed into larvae, and a still 

 greater part of those that had been in the hypertonic solution 

 for thirty-three minutes developed. A large number of these 

 larvae rose to the surface. If the eggs had been in the NH4OH 

 solution without KCN an exposure of fifteen minutes to the 

 hypertonic solution would have been sufficient. 



It should also be remembered that the writer had shown 

 long ago that the action of the hypertonic solution requires 

 also the presence of free oxygen and is del^-yed through the 

 addition of KCN. When the eggs are put into the alkaline 

 solution containing KCN for forty minutes they will not at 

 once lose all the KCN or HCN when put into the hypertonic 

 solution. This may. be an additional reason for the necessity 

 of keeping them longer than fifteen minutes in the hypertonic 

 solution after a treatment with a KCN solution. 



8. Effect of the concentration of NHiOH 



In all the experiments mentioned thus far the concentration 

 NH4OH used was 3/5000 N (0.3 ^ NH4OH) to 50 cc. m/2 (NaCI 

 + KCl + CaCl2), since this concentration was found to be very 

 satisfactory for the production of good larvae. It was desir- 

 able to get an idea of the limits of the concentrations in which 

 the NH4OH can be used. To 50 cc. m/2 (NaCl + KCl + 

 CaCl2) were added 0.05, 0.1, 0.2, 0.4, 0.8 cc. ^ NH4OH and 

 unfertilized eggs were put into these solutions. The eggs re- 

 mained in the solutions forty minutes and were then trans- 

 ferred into the above mentioned neutral hypertonic solutions. 

 They remained in the hypertonic solutions for fifteen minutes 

 and were then transferred to normal sea water. The results 

 are indicated in the following table: 



