86 



MARY GRACE SPRINGER. 



B and A showed many extreme modifications of form. Only 

 a few plutei developed. A' and B' showed plutei better de- 

 veloped. In all the other cultures with and without extract, 

 plutei were found, although many variations from the normal 

 type were noted. 



A separate control of eggs in sea water was kept. This showed 

 a general retardation of development in all the cultures and con- 

 trols containing even a small per cent, of acid. 



Conclusion. In the cultures containing extract an added re- 

 tardation was shown when comparison with the controls was 

 made. This retardation occurred chiefly at the early non-motile 

 blastula stage. 



Series 59. 



In this experiment the extract was made of ciliated blastulse 

 in a solution of ether and water (i part of ether to 2 parts of 

 water, distilled). The water was used merely because it is very 

 difficult to wash the extract from the sand by ether. Since water 

 and ether are only very slightly miscible, the extract had to be 

 shaken very vigorously before it was used. 



TABLE VIII. 



Later Development and Fate. A and A' showed very irregular 

 cleavage from the first. Development in B and B' , C and C' 

 was very nearly parallel through the motile blastula stage, but 

 A, B, and C showed retardation in their development from the 

 blastula stage to the pluteus stage. When the cultures were ex- 



