74 LON A. HAWKINS 



see table I), with and without additional Ca(NO 3 ) 2 , were also subjected 

 to potentiometer determinations of the concentrations of copper ions present 

 therein. In neither case was there any difference in electrical potential 

 between the two corresponding solutions. It is therefore clear that at least 

 99 per cent, of the Cu(NO 3 ) 2 is to be considered as dissociated in these 

 solutions, whether the calcium salt be present or not (see table I, C, b). 



From the foregoing considerations, it seems quite clear that the influence 

 of Ca(NO 3 ) 2 in reducing the toxic effect of Cu(NO 3 ) 2 on the germination 

 of the spores here employed 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 influence must be effective 

 upon the spores themselves, so altering them that they 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 protoplasm, or whether this toxic influence 

 is exerted primarily upon the spore walls or upon the surface film of the 

 protoplasm, thus perhaps creating some disturbance in physico-chemical 

 equilibrium that may subsequently be propagated inward, is a question for 

 the answering of which no evidence is yet at hand. Nevertheless, the present 

 studies have clearly demonstrated that the presence of Cu(XO 3 ) 2 alone 

 in the medium inhibits germination if the concentration be above a very 

 low limit, produces markedly altered forms of renewed activity if the con- 

 centration is somewhat lower., and allows normal germination only when 

 the solution is exceedingly dilute. While these facts must be interpreted 

 to mean that the copper salt tends to upset the protoplasmic system in some 

 way and that it is possible for that system to be so disturbed as either to 

 inhibit germination absolutely or to allow this process to proceed in modi- 

 fied form, yet much more direct evidence of such protoplasmic disturbance 

 was frequently met with in the progress of this work. Spores in which 

 all germinational activity had been prevented by the presence of Cu(NO 3 ) 2 

 frequently possessed a characteristic, coarsely granular appearance, as 

 though a precipitate or coagulum had been formed within the protoplasm. 

 Furthermore, this same appearance was often encountered in spores which 

 exhibited modified germination under the influence of copper. From this 

 it appears that the granular appearance of the protoplasm does not neces- 

 sarily denote death, but to settle this point conclusively and to determine 

 whether the production of apparent granulation might not be a post mortem 

 effect, the following experiment was performed. 



Spores which had been for eighteen hours in cultures with 0.00008111 

 solution of Cu(NO 3 ) 2 alone were employed. In this solution no germina- 

 tion has ever been found, in the more than twenty separate cultures which 



