270 



LEIGH HOADLEY. 



Table Via. 



Concentration of Per Cent. Per Cent. 



HgCh in Sea-water. Membranes. ist Cleavage. 



i : 1,000,000 ioo 16 



i : 800,000 100 12 



1 : 600,000 100 o 



1 : 400,000 100 o 



1 : 300,000 100 o 



1 : 200,000 100 o 



1 : 100,000 52 o 



1 : 75,000 48 o 



Inseminated control in sea-water 100 100 



Uninseminated control in sea-water. . o o 



Test with HgCh. July 11, 1922. 11 : 20 A.M. Eggs and sperm fresh. 

 Insemination 1 : 25 : 7.5. Eggs 9 C. Temp. 20° C. Concentrations greater 

 than 1 : 300,000 showed cytolysis in 20 minutes. 



For example, an examination of Table Via will show that at 

 1 : 600,000, HgCU is toxic to cleavage, while there is 100 per 

 cent, elevation of membranes which are wide and to all appear- 

 ances absolutely normal. In those concentrations in which 

 cleavage does not follow membrane elevation, cytolysis com- 

 mences within an hour for those eggs with membranes. Eggs 

 without membranes are more resistant. It appears from Table 

 VI6 that at I : 7,500 HgCl 2 , membranes are not raised. At 

 first glance it would be thought that this is a direct inversion of 

 the ratio found to hold for the other metals where membrane- 

 inhibition occurs at a lower concentration than cleavage-toxicity. 

 An examination of the effect of such a solution on the sperm 

 shows that they are instantly paralyzed by it and that this 

 paralysis is not reversible, i.e., neither NaOH nor concentrated 

 egg sea- water will activate the sperm in it. This immediately 

 differentiates such membrane-inhibition from that described for 

 the other metals. 



Lillie ('21) notes that the action of HgCl 2 is very different 

 from that of CuCl 2 . He notes that "the initial stages are 

 relatively little affected, . . . the susceptibility increases as 

 fertilization progresses" (page 140). He also notes that "mer- 

 cury also suppresses the movements of the spermatozoa at great 

 dilution." According to his data (Table VII.), a concentration 

 of 1 : 625,000 completely inhibits cleavage while I : 15,625 

 prevents membrane elevation. He states further, that at the 

 latter concentration, sperm are "paralyzed instantly." My 

 observations are in accord with the above, save that it was found 



