FERTILIZATION-REACTION IN ECHINARACHNIUS PARMA. 295 



fertilization but the control eggs may yield no fertilization. 

 Freshly liberated eggs may be and often are inferior to these 

 butyric acid treated eggs : they vary in size, in regularity of cleav- 

 age, and in vigor of larvae. 



The normally shed eggs of Echinaraclmius allowed to stand in 

 sea- water exhibit certain changes such as loss of jelly, change in 

 size, etc., to complete cytolysis the beginning of which is the swell- 

 ing of the cortex. If during the interval between shedding and 

 complete disintegration the time of which varies with temperature 

 and with different lots of eggs we inseminate these staling eggs 

 periodically, we obtain additional evidence of physiological de- 

 terioration. For the uninseminated eggs of Echinarachnius the 

 sea-water has an injurious action which manifests itself subse- 

 quent to insemination through the inability of the eggs to produce 

 membranes, the loosening of blastomeres during cleavage, the 

 production of aberrant larval forms, etc. (cf. Goldfarb's studies). 

 Against this cytolytic effect of sea-water short treatment with 

 butyric acid protects, the eggs cytolyzing at a slower rate and re- 

 taining fertilizing power for a longer period. It is only after 

 several hours that these butyric acid treated eggs fail to respond 

 to insemination. 



Although the short exposure to butyric acid is thus beneficial 

 in conserving fertilization power, longer exposures are decidedly 

 harmful. An exposure of ninety seconds, for example, may be 

 sufficient to bring about the complete loss of fertilizability within 

 an hour. Such an exposure is beyond the optimum for activa- 

 tion and does not result in activation because the activated egg, 

 which is the egg with full membrane, loses instantly with activa- 

 tion its capacity for fertilization. Over-exposure is comparable 

 to prolonged staling in sea-water inasmuch as the effect of either 

 is first to destroy the membrane, but the activable substances re- 

 main, albeit the long exposure has injured the egg, as evidenced 

 through its jelly-like cortex, and the egg develops on insemina- 

 tion without membrane lifting. Failing of insemination the over- 

 exposed egg soon loses its fertilization capacity because of the 

 onset of death changes that manifest themselves in the thick- 

 ening of the cortex which is the beginning of cytolysis. 



In conclusion, these observations on the duration of the fer- 



