FERTILIZATION-REACTION IN ECHINARACHNIUS PARMA. 287 



This observation demonstrates that while every egg of the 

 over-exposed dishes is in cytolysis more than half the eggs of 

 the 35 and 40 seconds exposures are intact and perfect in appear- 

 ance. The large body of data universally shows that though 

 cytolysis in over-exposed eggs may begin within an hour after 

 exposure, the case is different for the eggs with membranes which 

 are largely intact several hours after exposure. The membrane 

 formation in these eggs is not therefore per se the cause of cytol- 

 ysis. Moreover, here again as in other cases cited we note the 

 beneficial effect of short exposure to butyric acid in arresting the 

 normal cytolytic action of sea-water. 



Experiment 10 B. June 24, 9:00 A.M. Eggs exposed to 

 butyric acid sea-water from 15 to 120 seconds. Control in sea- 

 water. At 3 : 30 P.M. 6}/2 hours after treatment eggs ex- 

 amined for cytolysis. Another examination at 8:30 A.M., June 

 25. The counts of these two examinations are as follows : 



Comparison of the percentages of cytolyzing eggs six and one 

 half hours and twenty-three and one half hours after treatment 

 with butyric acid clearly shows that the cytolysis of eggs exposed 

 for the optimum length of time is of a different order from that 

 of over-exposed eggs. This was brought out repeatedly in the 

 observations. Over-exposed eggs cytolyze rapidly because they 

 are over-exposed ; eggs with membranes cytolyzt despite the fact 

 that they have membranes. 



Experiment Jj B. June 25, 11:20 A.M. Eggs from one 

 female washed in 10 c.c. of sea-water twice in ten minutes. Sam- 

 ple removed to normal sea-water as control (No. i) ; remaining 

 eggs exposed to butyric acid sea-water for 15, 20, 25, 30, 35, 40, 

 60, 90, and 120 seconds. 



