CELL DIVISION — SPINDLE IN SEA-URCHIN EGGS 



215 



and named the'amas sarcodique.' It later becomes converted 

 into the spindle, its end forming the material for the asters. I 

 shall, for convenience, refer to it as the 'pre-spindle.' 



Of course, with centrifuge tests every four minutes, it was 

 impossible to keep the eggs under constant observation. Ac- 

 cordingly, I could not record the exact minute when the pre- 

 spindle first appeared. Nevertheless, in some of the experi- 

 ments, I was able to fix the time of its appearance within narrow 

 limits. And this is all that could be hoped for, anyway. 



These observations and measurements of the living egg might 

 well be supplemented by observations and measurements of eggs 

 fixed after being centrifuged. I hope to make such a study at 

 some time in the future. 



I pass now to the consideration of individual experiments: 



Eggs fertilized at 10:35 a.m. 



„ ^ f22.3° at 10:35 A.M. 



Temperature 23,30 ^t 11^30 ^_^_ 



