Artificial Parthenogenesis m Starfish Eggs 



417 



TABLE IX 



August 2J. Eggs were removed at g:45 a.m.; left 50 minutes in normal sea-water; then transferred to 

 Ti^.TT KCN, and after the designated intervals warmed to 55° for "JO seconds in this solution, from 

 which they were transferred directly to sea-water; this was changed twice to remove all traces of cyanide 



Control warmed in normal sea-water: Three portions warmed respectively 30, 40 and 50 minutes after 

 removal gave only a few small abnormal blastute. 



Sperm-fertilized control: Portions were fertilized 30 m., 49 m., I h. 11 m., I h. 27 m., I h. 55 m., 2 

 h. 55 min., 4 h. 20 m. after removal; in the best cultures (30 m. and 49 m.) only one-third to one- 

 half of the eggs formed blastulas of which a large proportion were abnormal. 



In experiments 3 to 7 many eggs cleave irregularly and stop short in early cleavage stages. A remark- 

 able peculiarity of such eggs is that after 24 hours the blastomeres still remain clear and uncoagulated 

 and apparently living, though undergoing no further cleavage. This condition is in striking con- 

 trast to the fate of eggs fertilized either normally or artificially without cyanide treatment and whose 

 development also ceases in early stages; in such eggs the blastomeres rapidly undergo the typical coagu- 

 lative disintegration characteristic also of mature unfertilized eggs. The cyanide has apparently per- 

 manently modified the cell-protoplasm in such a manner as to check or prevent the oxidations on which 

 this breakdown depends. 



A third similar series (August 23) should also be mentioned 

 briefly. In this series the control eggs, warmed in normal sea- 

 water without previous cyanide treatment, gave no swimming 

 larvae; and the sperm-fertilized eggs gave only a few, from a por- 

 tion fertilized about 40 minutes after removal; these fertihzed 

 later (i h. 10 m., i h. 25 m., i h. 50 m, 3 h. 15 m. and 5 h. 15 m.) 

 gave no larvae. The eggs were thus typically "unfavorable." 

 A portion of the unfertilized eggs was placed in 2/00 KCN 30 min- 



