88 



MARY GRACE SPRINGER. 



Conclusion. A definite retardation was noted in the cultures 

 containing extract at the early blastula stage and afterwards. 



Series 53. 



Extracts made up in alcohol (C 2 H 5 OH) must be used in small 

 amounts, or else the alcohol must be a very weak solution, for if 

 the concentration of alcohol in the cultures reaches three or four 

 per cent, so many deaths occur in the blastula stage that compari- 

 son with the controls is difficult. Five series of experiments 

 proved unsuccessful on this account. 



In the experiment outlined below the extract was made up in 

 15 per cent, alcohol, and allowed to remain in the tightly corked 

 tube for 24 hours before using. 



TABLE XL 



Later Development and Fate. Very irregular cleavage in A 

 and A'. No apparent difference between B and B' , C and C 

 at the blastula stage. 

 Later: C' many normal plutei. 

 C a few normal plutei. 

 B and B' B very slightly retarded, with fewer and smaller 



plutei. 

 A and A' as B and B', with greater retardation in A 



than in B. 



Conclusion. Since alcohol, even in very weak concentrations, 

 has such a powerful effect on the developing eggs, no very definite 

 conclusion can be drawn from this series of experiments. 



