414 E - E - JUST. 



A2, E>2, 2 : i drop of shed eggs plus 2 drops of blood insemi- 

 nated in sea-water. 



A^, 3, 3 : i drop of shed eggs plus 4 drops of blood insemi- 

 nated in sea-water. 



A4, B^, 4 : i drop of shed eggs plus 8 drops of blood insemi- 

 nated in sea-water. 



10 : oo P.M. Ai, Bi, Ci show 96, 98, and 93 per cent, fertiliza- 

 tion, respectively. No development in other dishes. 



July 17, 10:30 A.M. Nos. A2, 82, and 2 show about .01 

 per cent, development. No development in the others. 



Nos. A2 to 4, inclusive, washed and set aside. 3:00 P.M. 

 No cleavage. Samples from each of these inseminated. 3 : 10 

 P.M. Good membranes in most eggs of Nos. A2 to C$, inclusive. 

 Nos. A4 to 4 only about 40 per cent, membranes each. 



3 : 45 P.M. First cleavage in all eggs that have membranes. 



7:30 P.M. Other samples from the eggs A2 to 4, inclusive, 

 which were washed this morning inseminated. 



9 : oo P.M. About .01 per cent, in two-cell stage in 82. No 

 development in others, though numerous sperm attached. All 

 dishes show active sperm. 



July 18, 8:00 A.M. One blastula in B2. 



This experiment and others of this group show several points. 

 They show that shed eggs of high fertilization capacity will not 

 fertilize in the presence of blood. The amount of blood necessary 

 to bring about this inhibition can not be predicted because the 

 inhibitory power of the blood of various females is not exactly the 

 same. In this group of experiments, however, made usually with 

 eggs from different females in samples of the same blood, the 

 results are fairly constant ; the inhibition to fertilization is about 

 the same. Finally, the experiment indicates that twenty-six and 

 one half hours after insemination in the presence of blood eggs 

 may on reinsemination be made to develop. Usually such capacity 

 to respond to reinsemination does not persist after twenty-four 

 hours. As Lillie has shown, the presence of blood does not inter- 

 fere with the action of the sperm agglutinin (fertilizin) produced 

 by Arbacia. It would have been interesting to compare the pro- 

 duction of fertilizin by these eggs inseminated in blood with that 



