FERTILIZATION REACTION IN ARBACIA PUNCTULATA. 



26l 



Table la. 



Concentration of AuCh in Sea-water. 



Per Cent. Membranes. 



9 A. 9 B. 



Per Cent. 1st Cleavage. 



9 A. 



9 B. 



1 : 12,000,000 



1 : 6,000,000 



1 : 3,000,000 



I : 1,500,000 



1 : 1,200,000 



1 : 600,000 



1 : 300,000 



Uninseminated control in sea-water 

 Inseminated control in sea-water . . 



100 



68 



22 



o 



100 

 20 

 2 

 o 

 o 

 o 

 o 

 o 



100 



99 



69 



20 



o 



o 



o 



100 



18 



o 

 o 



100 



Effect of AuCh on eggs inseminated therein. July 20, 1922. Temp. 22.5° C. 

 Eggs and sperm fresh. Insemination immediate 1 : 25 : 7.5. 



tion in normal sea-water. The results for one of these tests is 

 given in Table lb. Table lb shows the concentration of AuCl s 

 toxic to cleavage to be 1 : 375,000. Comparison with Table la 

 brings out the difference between membrane-inhibiting and 

 cleavage-toxic concentrations. 



Table lb. 



Concentration Per Cent. Per Cent, 



of AuCU in 1st Cleavage. 2d Cleavage. 



Sea-water. 



1 : 1,500,000 90 3 



1 : 750,000 12 o 



1 : 375.ooo o o 



1 : 185,000 o o 



Inseminated control in sea-water .... 98 97 



Test of cleavage-toxicity of AuCh. July 20, '22. Eggs from 9 A. Opened 

 1 : 34 P.M. Membranes 100 per cent. Eggs transferred to solution five minutes 

 after insemination in normal sea-water. 1:25:7.5. Sperm fresh. Temp. 24 C. 



In Table Ic can be seen viability tests run with the same lot 

 of eggs at both the cleavage-toxic and the membrane-inhibitory 

 concentrations. This test shows the difference between these 

 two kinds of action. A concentration that is completely inhibi- 

 tory to the initial events has no absolute effect on the subsequent 

 events, while a more concentrated solution will prevent the 

 occurrence of the subsequent events provided the time factor is 

 sufficient. The effect of the exposure time is also shown by this 

 table. The effect on cleavage is cumulative. The higher the 

 concentration of the metallic salt, the shorter need the time of 

 exposure be, to produce complete inhibition. 



