Artificial Parthenogenesis in Starfish Eggs 



421 



The following series will illustrate: 



TABLE X 



Series I. September 7. Eggs were transferred 30 minutes after removal from the animal, to sea-water 

 containing .-,^5^ KCN; after an interval of ca. 40 minutes they were warmed in this solution to 

 55° for "JO seconds; thence transferred to cyanide solution at normal temperature; from this, after the 

 designated intervals, portions were transferred to normal sea-water. 



Controls warmed in normal sea-water 35, 45 and 55 minutes after removal gave considerable numbers 

 of good larvae. 



Sperm-fertilized control, fertilized one hour after removal, gave also a large proportion of larvae, though 

 fewer than in the best experimental cultures; development was also less rapid. 



A number of eggs were left in the KCN solution after warming until next morning (23 hours); they 

 were then clear and uncleaved and all had typical membranes. On transfer to normal sea-water none 

 underwent development, and next day all were dead and disintegrated. 



In the above series of experiments a marked increase in favor- 

 abihty resulted from the brief after-treatment with cyanide. In 

 those next to be described a greater range of exposure to the cya- 

 nide solution was employed; otherwise the procedure was the 

 same. 



