Artificial Parthefwgeiies/s iti Sfar/ish Eggs 423 



solution for some minutes after warming gave decidedly better re- 

 sults than were obtained from eggs transferred directly to sea-water 

 without after-treatment with cyanide. The eggs were removed 

 from the animal at 10 a.m. September 4, 1907; at 10:35 ^^^Y were 

 placed in ^-^^ty KCN; and after 55 minutes were warmed to 35° 

 for 70 seconds and then replaced in cyanide solution at normal 

 temperature, whence, after the intervals used, they were transferred 

 to normal sea-water. Here the eggs brought into sea-water 

 directly after warming in cyanide solution gave no larvae; while 

 eggs after exposed to cyanide for only 5 minutes yielded consider- 

 able numbers of good gastrulae, proving in fact more favorable 

 than the best sperm-fertilized control; 10 minutes after-treatment 

 on the other hand gave few larvae; and eggs left respectively 20, 

 35 and 50 minutes in cyanide after warming gave successively 

 fewer and fewer; while none resulted with after-exposures of 

 I h. 10 m., I h. 30 m., 2 h. 50 m. and 4 h. 20 m. 



These experiments indicate clearly that checking of oxidation 

 processes during a certain interval after warming acts favorably 

 under certain conditions; if this interval is prolonged for more 

 han a few minutes conditions become rapidly less favorable, 

 possibly, as suggested above, in consequence of the progress of 

 certain hydrolytic processes unaccompanied by oxidations. The 

 striking increase in the proportion of developing eggs under the 

 treatment used above, and also in the rate and normality of the 

 development, suggests strongly that anaerobic conditions — at 

 least at certain stages — form an important factor in the initiation 

 of development in starfish eggs. Oxygen is necessary to the 

 developmental process itself; but the internal changes that impart 

 to the egg the distinctive power of automatic development seem 

 best induced under conditions that must very effectually prevent 

 most intracellular oxidations — at least those conditioned by the 

 presence of enzymes. The above results indicate therefore that 

 momentary elevation of temperature — assuming that its essential 

 action is the acceleration of chemical processes in the egg-sub- 

 stance — must affect primarily other processes than the oxidative; 

 in brief, acceleration of these processes, presumably hydrolytic in 

 nature, simultaneously with a suppression of oxidations, appears 



