Artificial Parthenogenesis in Starfish Eggs 



TABLE V— Continued 



403 



I find no record in my notes of the condition of the membranes in Experiments 12 to 14 of Series II. 

 In this series membrane-formation is not so completely absent as in Series I in the stages succeeding 

 the completion of maturation; but presumably the proportion of eggs without membranes increased 

 steadily from Experiment 1 1 to Experiment 16 where only a few were formed. 



In both of the above series the eggs show a progressively increas- 

 ing inability to respond to momentary warming after the maturation 

 process is complete. The proportion of eggs that fail to form mem- 

 branes also increases with the lapse of time in the post-maturation 

 stages. Cleavage becomes irregular or fails altogether; the 

 curious result also appears in the experiments made some time 

 after the complete separation of the second polar body that the 

 tendency to coagulation, typical of mature unfertilized eggs, is 

 markedly accelerated. This effect is conspicuous in eggs warmed 

 at a stage of four or five hours after removal, as seen in both of the 

 above series; the coagulative process is well advanced in such eggs 

 within three or four hours after warming; while in mature eggs not 

 exposed to this treatment, or warmed at an earlier stage, coagulation 

 does not become evident until some hours later. The process, as 

 Loeb has shown, is oxidative in nature; warming in post-matura- 

 tion stages has thus the effect of accelerating oxidations leading 

 to a coagulative disintegration of the egg-substance. An earher 

 experiment performed with another object in view shows the same 

 result: Eggs were removed at 11:30 a.m. August 5, 1907; about 



