9 o 



MARY GRACE SPRINGER. 



statement seemed to hold good for the early cleavages, since there 

 was no definite increase in rate observed there, but that the rate 

 of development from blastula to pluteus was accelerated. It 

 would appear, however, that from Loeb's account of his experi- 

 ments, the acceleration mentioned in the first paper was not 

 observed until after the first day, so that there is after all no 

 disagreement between the results obtained by these two in- 



vestigators. 



TABLE XII. 



Note. The time recorded under the cleavage rate is the num- 

 ber of minutes between insemination and the first appearance of 

 the stages indicated. 



Later Development and Fate. It is evident that there is only 

 a very slight retardation, if any, in the cultures containing the 

 extract in small amounts during the early cleavages. 



At a later reading A was found to contain non-motile blastulae, 

 A' motile blastulse. In B and B' ' , C and C' no considerable dif- 

 ference was observed, except for the fact that in B' the blastulse 

 appeared to be swimming more vigorously than in B. 



Still later, the reading showed the late gastrulae in A dead 

 while in A' were found some plutei of varying abnormality. 



B a few plutei, varying somewhat from the normal. 



B' flourishing plutei, varying somewhat from the normal. 



C as B; C' as B'. 



The controls in sea water showed more rapid and normal de- 

 velopment at all stages. 



Conclusion. A very slight retardation was produced by the 

 use of the extract in the early cleavage stages. This effect was 

 more evident from the blastula to the pluteus. 



