ORIGINAL METHOD OF ARTIFICIAL PARTHENOGENESIS 165 



2.0 c.c. N/10 NaOH, 0, 2, 4, 8, and 16 c.c. of 2J m KC1 were 

 added. Unfertilized eggs were divided among these five solu- 

 tions and portions of the eggs transferred to normal sea-water 

 after 45, 64, 89, 116, and 144 minutes. The results are sum- 

 marized in Table XXXIII. The increase of osmotic pressure 

 is given in the table in round numbers as a percentage of the 

 pressure of the half grammolecular solution. 



TABLE XXXIII 



TIME OF 



INCREASE OK THE OSMOTIC PRESSURE OF THE SOLUTION 



Further experiments on the eggs of S. purpuratus showed 

 that the results remain the same if the two agencies, the base 

 and the neutral hypertonic solution, are applied in succession 

 instead of simultaneously. When the treatment of these eggs 

 with the alkaline solution (added to a neutral isotonic solution) 

 preceded their treatment with a neutral hypertonic solution, 

 it could be seen that the former agency acted mainly as the 

 membrane-forming agency, while the hypertonic solution acted 

 as the corrective agency. 



For the egg of Arbacia a neutral hypertonic solution suffices 

 to call forth a normal development. 



3. Why should the addition of alkali to the hypertonic 

 solution increase its efficiency? The answer is that the ad- 

 dition of alkali increases the membrane-forming effect of the 

 hypertonic solution. In S. purpuratus the hypertonic solution 



