EGGS OF ASTERINA (PATIRIA) MINIATA. 109 



IV 6 No membranes and no cleavage. 



8% About 2 per cent, of eggs cleaving without mem- 

 brane formation, some as advanced as 8 cells. 



25 Nearly 2 'per cent, blastulae, slightly abnormal and 



motionless. 



V 6 l / 2 About 5 per cent, of eggs with rather narrow but 



distinct membranes, no cleavage. 



jT/2. About i l /2 per cent, of eggs without membranes in 



early cleavage stages (2, 3, 4 cells), some quite 

 regular, but the majority more or less irregular. 



8J^ About 5 per cent, of eggs cleaving, ranging from 2 



to 1 6 cells. Evidently a good deal of cleavage 

 has begun since the 7^2 hour observation. A few 

 of the eggs now show wide typical membranes 

 and there are transitional stages between these 

 and the more plentiful type with narrow mem- 

 branes. 



26 About 7 per cent, swimming blastulse, some nearly 



normal, but the majority solid, wrinkled or other- 

 wise abnormal. Eggs with membranes, under- 

 going black cytolysis. 



31 Many gastrulaa, some with two or more archentera 



some exogastrulae, etc. 



74 A good collection of twin larvae, studied in a subse- 

 quent connection. No normal larvae. All larvae, 

 swimming on the bottom of the dish. 



VI 6% About 4 per cent, of eggs with distinct but narrow- 

 membranes, no cleavage. 



8% About 2^/2 per cent, of eggs with wide, typical 



membranes, but no egg with membrane shows 

 cleavage; about ^2 of i per cent, of eggs showing 

 cleavage stages, ranging from 2 to 8 cells, some 

 quite regular. 



2& l /2 A very few larvae, all subnormal, some motionless, 



others feebly swimming. 



VII 7 No membranes, no cleavage. 



9 No membranes, but about 2 per cent, of eggs in 



cleavage stages ranging from 2 to 32 cells. 



z6 l /2 About i per cent, subnormal blastulae, a few swim- 

 ming. 



32 A very few larvae undergoing gastrulation ; several- 



with two or more archentera. 



VIII 6^2 No membranes, no cleavage. 



9 No membranes, but about 3^2 per cent, of eggs in 



cleavage stages, ranging from 2 to 16 cells. 

 26 About 2 l / 2 per cent, of larvae, all subnormal. 



