INITIATION OF DEVELOPMENT IN EGG OF ARBACIA. 419 



11:48 A.M. Ovaries of each of above females (Nos. i to 9, 

 inclusive) separately chopped up in sea-water; strained. Each lot 

 of eggs in 200 c.c. of sea-water. 



ii : 55 A.M. Portions of each lot of eggs inseminated. 



2 : oo P.M. Beautiful cleavage in all lots close to 100 per cent. 



At times the quantity of eggs that exude from the genital pores 

 is really enormous for the size of the urchin. Such eggs are per- 

 fectly beautiful. And yet the bulk of the eggs is no criterion for 

 their fertilizability. I have used eggs from animals fresh from 

 the sea. The results are the same; they are not due to the fact 

 that the animals have deteriorated in the laboratory. 



The protocols herewith cited (Sections A and B) constitute the 

 evidence for the conclusions that eggs of Arbacia vary with re- 

 spect to their fertilization capacity during the summer ; during the 

 first part of the season shed eggs possess high fertilization capacity 

 which drops off during the latter part of the season ; eggs from the 

 ovary, during the latter part of the season when the shed eggs are 

 poor, possess high fertilization capacity. A simple method is 

 thus indicated for obtaining throughout the summer eggs of high 

 fertilizability. The evidence likewise admits of the conclusion that 

 blood blocks fertilization in shed eggs of high fertilizability. It is 

 likewise true, though no experiments have been cited on this point 

 in the present paper, that fertilization of eggs from the ovary with 

 high fertilization capacity is blocked by blood. The findings of 

 the writer as to this effect of blood on eggs of Arbacia are thus in 

 accord with those of Lillie ('14). 



The experiments cited above also show that eggs in the presence 

 of blood agglutinate to themselves and even take in sperm, and 

 that such sperm may activate at any time during a dormant period 

 of about two hours if the blood is removed by washing. Finally, 

 the experiments reveal that as long as twenty-eight hours after 

 insemination in the presence of blood eggs failing to develop may 

 do so on reinsemination. In view of Lillie's recent work ('21) on 

 the effect of copper salts in fertilization especially important in 

 revealing the latent period in the fertilization-reaction these find- 

 ings of mine may deserve notice since they lend additional support 

 to Lillie's fertilizin theory. 



The protocols here given do not, however, establish that blood 



