EFFECT OF EXTRACTS UPON DEVELOPING EGGS. 



amined later, C' had many normal plutei ; C had just a few small 

 plutei, swimming feebly. B and A were retarded in their de- 

 velopment, with fewer and smaller plutei than those in B' and 

 A'. A showed by far the largest number of abnormal forms. 



Conclusion. A retardation was noted especially between the 

 blastula and the pluteus stages in the etherial extract cultures. 



Series 45. 



The extract used in this experiment was made by soaking the 

 embryos (motile blastulae) after the usual crushing process, in a 

 solution of one part of acetone in one part of distilled water, for 

 12 hours. This same solution was used in preparing the controls, 

 and was always shaken vigorously before using. 



TABLE IX. 



Later Development and Fate.- Development in the cultures and 

 the controls appeared to be very nearly parallel until the early 

 non-motile blastula stage. At that point in development blastulae, 

 some swimming vigorously, were found in A while in A' most 

 of the blastulae were non-motile, although a very few were mov- 

 ing feebly. In B and B', C and C' there was also an evident 

 retardation, although it was not so great as that registered in the 

 A and A' cultures. 



On the following day these readings were made : 

 A very early plutei; A' a very few late gastrulse; B early 

 plutei ; B' very early plutei ; C and C' no difference apparent. 

 A few late blastulae, but mostly early plutei in both. 



