THE PERMEABILITY OF THE EGG MEMBRANE. 



383 



Experiment V. The same seven salts used in Experiment III. 

 were used in ^ //. solutions. The same method of procedure 

 was used throughout as in Experiment III. and the results are 

 given in the following table. The experiment was performed 

 twice and the figures are given side by side for the sake of 

 comparison. 



Averaging the percentages of cleavages in the two experiments 

 we find that the salts arrange themselves as follows : CaCl. 2> 4.4 ; 

 Bad,, 10.1; SrCl 2 , 15.6; MgCl 2 ,i8; LiCl, 62.5 ; NaCl, 78 ; 

 KC1, 88. This corresponds exactly with the order of the pre- 

 cipitating power of these salts on colloidal egg albumin and pos- 

 sibly with the order of the solution tensions of these cations. 



These results seem to indicate that the cause of the inhibition 

 of fertilization is of the nature of a precipitation of the colloids of 

 the egg membrane. In order to demonstrate the possibility of 

 rendering the egg impermeable to sperm of the same species and 

 then reversing the coagulation so as to restore its permeability, a 

 y 2 Q- n. CaCl 2 solution was used as a precipitating or coagulating 

 agent and a m/io Na.,So 4 solution was used as a salt which theo- 

 retically should reverse the coagulation. 



Experiment VI. A lot of eggs were stripped into 100 c.c. of 

 y 2 Q- n. CaCl 2 solution and after a five minute exposure were divided 

 into two dishes, one containing ;///io Na,So 4 and the other con- 

 taining sea water as a control. The control eggs were imme- 

 diately mixed with an abundance of sperm, which was allowed to 

 remain in the dish, but not a single egg cleaved. The eggs 

 transferred to the m/io Na.,So. solution were allowed to remain 



jL - 



there for twenty minutes and were then transferred to sea water 

 and fertilized. It was found in the course of about three hours 

 that 27 out of 88 eggs had cleaved. The experiment was re- 



