STUDIES OF FERTILIZATION. 



233 



quantities of washed eggs were put in measured amounts of sea- 

 water, and measured quantities of definitely calibrated sperm 

 suspensions added and stirred in as uniformly as possible. 



A control of unfertilized eggs in sea-water was always kept to 

 guard against chance fertilizations. To illustrate: the last four 

 determinations of the curve were made as follows: In four 



