INITIATION OF DEVELOPMENT IN EGG OF ARBACIA. 413 



cuse watch glass and drained of fluid, removed to another watch 

 glass, and allowed to shed. The blood from each animal was used 

 separately or that from several animals united. After clotting, the 

 serum was decanted and set aside until needed. Sea-water in 

 which blood clots were cut up after filtering was used in one ex- 

 periment. It seemed no different in its action from the serum. 



A. 



We may begin with the experiments which indicate that during 

 the early part of the season Arbacia eggs that exude through the 

 genital pores are of high fertilization capacity. Blood added to 

 these eggs before insemination cuts down the per cent, of fer- 

 tilization. 



THE EXPERIMENTS. 



(a) July 14, 4:00 P.M. i drop of shed eggs from one female 

 in 10 c.c. of sea-water allowed to settle. Water changed three 

 times. Eggs inseminated Lot A. 



2 drops of shed eggs from same female in 5 c.c. of sea-water 

 plus 5 c.c. of blood. Allowed to settle, i drop of these eggs 

 removed to 10 c.c. of sea- water Lot B and inseminated. Re- 

 mainder of the same eggs inseminated Lot C. 



/ : oo P.M. These eggs give cleavage as follows : 



This experiment is typical of a group of experiments made dur- 

 ing the month of June and the first three weeks of July. I always 

 found some inhibitor present in the blood of females, though the 

 amount might vary to a considerable degree. Thus in some cases, 

 particularly in the early experiments, a great deal of blood from 

 several animals had to be used to inhibit fertilization. These 

 experiments, without a single exception, reveal a high capacity for 

 fertilization on the part of shed eggs. 



(&) July 16, 8:00 P.M. 4 drops of shed eggs from each of 

 three females (A, B, and C) distributed as follows: 



Ai, Bi, Ci: i drop of shed eggs inseminated in 250 c.c. of 

 sea-water. 



