FERTILIZATION REACTION IN ECHINARACHNIUS PARMA. 



19 



Controls : uninseminated eggs in normal sea-water ; inseminated 

 eggs in normal sea-water. 



The eggs were examined at intervals. The next day, 7 : 50 

 A.M., the uninseminated eggs (Series \A, IB, and IC) showed an 

 average of less than 10 per cent, cytolysis. The history of Series 

 II. is given in the table below (Table I.) : 



Table I. 



Per Cent, of Membranes and of Cleavage in Eggs of Echinarachnius In- 

 in Sea-water of Varying Dilution. 



This experiment indicates that eggs inseminated in dilutions of 

 sea-water may separate membranes, though they do not cleave. It 

 would, therefore, be erroneous to assert — if membrane separation 

 be the criterion for fertilization — that eggs that do not cleave have 

 not been fertilized. Rather the failure to cleave is due to the 

 action of the dilute sea-water in interfering with the cleavage 

 mechanism — particularly with the activity of the hyaline plasma 

 layer. There is no question here of " partial fertilization " ; it is 

 wholly a question of incomplete cleavage. This is important for 

 the experiments that we may now consider. 



In the experiments now to be considered it was repeatedly 

 found that eggs may be inseminated in a dilution that is destructive 

 to the egg which is inseminated in sea-water and exposed to this 

 dilution during membrane separation. The criterion of this de- 

 structive action is the differential cytolysis of uninseminated and 

 inseminated eggs before, during, and after membrane separation. 



