468 



ALVALYN E. WOODWARD 



sea-water trickled slowly. The eggs were washed in running 

 water in this manner for seventeen hours. These washed eggs 

 were then divided into lots B and C. To B fresh egg secretion 

 was added. All three were subsequently inseminated. In 

 spite of the time which had elapsed since the eggs had been 

 shed, a large number of the control, A, formed membranes. 

 About the same number formed membranes in B, the washed 

 eggs to which the secretion had been added, but in C, which was 

 practically free from fertilizin, none was formed. None of the 

 eggs developed beyond the eight-cell stage, doubtless due to the 

 long time that had elapsed between maturation and insemina- 

 tion. The addition of egg secretion had restored the washed 

 eggs to a fertilizable condition. 



If, at the height of the breeding season, the eggs of Asterias 

 or Arbacia are inseminated after the addition of fertilizin, the 

 proportion developing is not materially affected. However, 

 at the beginning or end of the season, a large part of the eggs are 

 resistant to sperm fertilization. If fertilizin be added at that 

 time, it will help to overcome this resistance as shown below: 



TABLE 21 



The effect of adding fertilizin to normal and to resistant eggs 



The result might be due to an increased permeability, since 

 Glaser found that fertilizin has such an effect. It is very likely, 

 however, that the resistance is due to lack of fertilizin, since egg 



1 Throughout the experiments, percentages have been reckoned from counts 

 of at least two hundred normal-appearing eggs. 



