37 



that is here dissociated; as has already been mentioned, 

 the solution would still be toxic enough to inhibit spore 

 germination in Gloesporium if only one per cent, of the 

 total Cu(N03)2 were dissociated. 



The remaining two concentrations of Cu(NC2)2 

 (0.0CC4m and O.CCClm, see the table already given), with 

 and without additional Ca(N03)2, were also subjected to 

 potentiometer determinations of the copper ions present 

 therein. In neither case was there any difference in elect- 

 rical potential between the two corresponding solutions. It 

 is therefore clear that at least 99 per cent, of the Cu(N03)2 

 is to be considered as dissociated in these solutions, wheth- 

 er the calcium salt is present or not. 



From the foregoing considerations, it seems quite 

 clear that the influence of CalNOg).-! in reducing the toxic 

 effect of Cu(NC3)2 on the germination of the spores here em- 

 ployed is not at all to be related to any changes brought 

 about in the solution itself by the addition of the calcium 

 salt. It appears that this antitoxic or antagonistic in-; 

 fluence must be effective upon the spores, so altering them 

 that they thus become capable of germination in solutions 

 whose concentration of free copper ions would inhibit this 

 process were it not for the presence of the calcium salt. 



Whether the copper enters the spores and exerts its 

 toxic action directly through some alteration in the proto- 

 plasm, or whether this toxic influence is exerted primarily 



