ACTIVATION OF UNFERTILIZED STARFISH EGGS. 26I 



down of the germinal vesicle and the separation of the first 

 polar body; after both polar bodies had separated development 

 was imperfect and never proceeded far, — even membrane-forma- 

 tion then failed in many eggs. 



Recent advances in the physiology of fertilization and artificial 

 parthenogenesis have made it desirable to examine these effects 

 of temperature in greater detail and to correlate them with the 

 similar effects produced by other agents. During the past 

 summer at Woods Hole I have accordingly re-investigated the 

 changes in unfertilized starfish eggs following exposure for 

 different periods to temperatures ranging from 28° to 36°, with 

 especial reference to the differences in physiological effect result- 

 ing from differences in time of exposure to a given temperature 

 (e. g., 32°), and also with reference to the manner in which the 

 time of exposure required to produce a given effect {e. g., mem- 

 brane-formation) varies at different temperatures. Determina- 

 tion of the temperature-coefficients of the processes underlying 

 these effects is likely to afford indications of the nature of the 

 fundamental changes concerned in the activation of the egg. 

 Experiments on the effects of exposure to weak fatty acid 

 solutions for different periods were also carried out; and on the 

 action of high temperatures (32° to 34°) and fatty acid solutions 

 on eggs which had previously been subjected to a membrane- 

 forming treatment. 



It is well known that the temperature-coefficients of a large 

 number of physiological processes have been found similar to 

 those of chemical reactions in general.^ This result is to be 

 regarded simply as an expression of the fact that the energy for 

 such processes is usually chemical energy freed by oxidations or 

 other reactions, whose rate accordingly determines that of the 

 process in question. There are, however, many instances in 

 which rise of temperature produces an entirely different kind of 

 effect. Often a process exhibits a critical temperature below 

 which it entirely fails to take place.- In such instances the 



1 For a summary account of researches in this field cf. C. D. Snyder: American 

 Journal of Physiology, 1908, Vol. 22, p. 309. 



2 Examples of such processes are : inactivation of enzymes and toxines or de- 

 struction of microorganisms by heat; heat-coagulation of proteins, and dependent 

 processes like injury or destruction of various cells by heat; onset of heat-rigor; 



