FERTILIZATION REACTION IN ARBACIA PUNCTULATA. 27 1 



necessary to use a concentration of I : 7,500 HgCl 2 to instantly 

 paralyze sperm and consequently to completely inhibit membrane 

 elevation (Table VI&). Lillie considered that the action of 



Table VI&. 



Concentration of Per Cent. Per Cent. 



HgCh in Sea-water. Membranes. ist Cleavage. 



1 : 75,000 86 o 



1 : 50,000 70 o 



1 : 25,000 40 o 



1 : 20,000 30 o 



1 : 15,000 . . . . : 20 o 



1 : 10,000 4 o 



1 : 7,500 o o 



Inseminated control in sea-water 98 99 



Uninseminated control in sea-water o o 



.Test of HgCh. July 21, 1922. 3 : 04 P.M. Temp. 26 C. Eggs 9 C. 

 Eggs and sperm fresh. Insem. 1 : 25 : 7.5. 



mercury on membrane-inhibition was like that of copper but at 

 a much higher concentration. I would prefer to consider that 

 the action of HgCl 2 is a poisoning of the sperm, and not the 

 type of inhibition that is present in copper-inhibition. 



In most of the metallic salt solutions, the effect is to make the 

 membranes narrow as the concentrations approach the strength 

 necessary for membrane-inhibition; HgCl 2 has exactly the 

 opposite effect. When eggs are inseminated in solutions which 

 do not paralyze the sperm, membranes elevate immediately and 

 such membranes are extremely wide. The solutions alone will 

 produce membranes on eggs in concentrations greater than 

 1 : 150,000 as has also been observed by Lillie ('21). These 

 membranes form much later than those produced by insemination 

 so that it is easy to differentiate between the two. Eggs with 

 membranes cytolyze very rapidly when left in HgCl 2 solution. 



It would thus appear that, in comparing the action of the 

 Mercuric salt with those of the metals already described, the 

 only great difference is in the failure of the HgCl 2 to show any 

 concentration which prevents the action between viable egg and 

 sperm and consequently the initial response of the cortex of 

 the egg. 



b. Comparative Tests. 



The preceding part is devoted to individual tests on the 

 behavior of various salts. These tests were made with separate 

 18 



