EFFECT OF EXTRACTS UPON DEVELOPING EGGS. 



81 



Note. The cleavage rate is given in terms of minutes between 

 insemination and a fifty per cent, development of the specified 

 stage. 



Later Development and Fate.- The controls developed faster 

 and more normally than did the other cultures, which were all 

 retarded in the early cleavage stages and at the non-motile blastula 

 stage. All the cultures finally developed into gastrulze. Some 

 exogastrulse were found in all the cultures containing extract. 

 No development beyond the late gastrula or very early pluteus 

 stage was observed in the cultures containing extract. 



The controls showed normal development. 



Conclusion. Definite retardation was noted in the cultures con- 

 taining extract and total arrest at the late gastrula or early pluteus 

 stages. 



Scries 26. 

 TABLE IV. 



Note. Under " cleavage rate " is noted the number of minutes 

 which elapsed between insemination and the appearance of the 

 first 2-, 4- or 8-cell stage. 



Later Development and Fate. Development to the gastrula 

 stage was nearly parallel in all the cultures. A did not develop 

 into very vigorous plutei ; B showed plutei a trifle smaller than 

 normal, while in C were found plutei, but many abnormal types. 

 All the controls had normal plutei. 



Conclusion. Slight retardation in cultures containing the ex- 

 tract or the " water." 



