Artificial Parthenogenesis in Starfish Eggs 419 



It is noteworthy that a certain time of exposure to the cyanide 

 sokition — apparently about one hour or somewhat less — produces 

 optimal conditions for development; after more prolonged expo- 

 sure warming tends to result in abnormal development; in Tables 

 VIII and IX the proportion of eggs that reach a larval stage is seen 

 steadily to diminish with increase in the time of exposure to the 

 cyanide beyond an hour or so, and the larvae tend to become 

 thick walled, irregular in shape, or otherwise abnormal. After 

 exposure for more than two hours to the cyanide few eggs develop 

 to a free-swimming stage. This change in the condition of the 

 eggs points to the existence of certain processes other than oxida- 

 tions which continue unchecked in the presence of cyanide; 

 there are no doubt hydrolyses of various kinds, and it may reason- 

 ably be inferred that both kinds of processes are concerned in the 

 changes that render the egg capable of parthenogenetic development. 

 Suppression of oxidations for a time, during which the hydrolyses 

 proceed unchecked, appears then to be favorable to bringing the 

 eggs into a condition in which they respond readily to momentary 

 warming; but if the hydrolyses unaccompanied by oxidations are 

 allowed to proceed too far, lack of coordination in the succeeding 

 developmental processes seems to result, as shown by the increased 

 proportion of unfavorably developing eggs. Normally a certain 

 balance between the oxidative and the hydrolytic processes must 

 exist; possibly a disturbance of this balance may be an important 

 condition in the initiation of the developmental process. Such 

 an interpretaton is at least suggested by the foregoing results. 



It should be pointed out that simple exposure to cyanide solu- 

 tions without warming has no influence in initiating development 

 in these eggs — at least under the above conditions. In the second 

 of the two series tabulated above a portion of eggs was transferred 

 from the cyanide solution to sea-water, without warming, at the 

 time of each experiment of the series. None of these eggs formed 

 merhbranes or showed any other sign of development and all were 

 dead and coagulated next morning. The momentary elevation 

 of temperature is thus essential. Since hydrolytic processes are 

 relatively unaflPected by cyanide, we may infer that hydrolyses are 

 accelerated to at least four or five times the original velocity during 



