2ti 



of thp Cvi(NC3)2 so as to produce on effect on spore germin- 

 ation equivalent to that exercised by a C.0G004m solution 

 of the copper salt alone. In other words, the addition to a 

 0.0CG4m Cu(NC,).-, solution of Ca(NC3)„ in the molecular ratio 

 of five of this to two of the copper salt has the same effect 

 as diluting the CuCNOgjo solution to ten times its original 

 volume. 



A third series of combinations of the same two salts, 

 but at somewhat higher concentrations ,was carried out in a 

 manner somewhat different from that of the preceeding series. 

 Here the concentration of the Ca(N03)2 ^^^s the same (O.C5m) in 

 alx of the cultures while that of the copper salt varied. 

 The concentrations of Cu(NC3)2 varied from C.0C025ra to 0.01m 

 and spores germinated in all concentrations except the high- 

 est. With a concentration of C.OOSm CuCNGslg germination was 

 similar to that found with C.0CC04m of the copper salt with- 

 out the addition of CaCNCj) . From this series it appears 

 that the addition to the Cu{NC )2 solution here used (C.OOSm), 

 of six molecules of Ca(NC3)2 for each molecule of the copper 

 salt present in the solution, reduces the toxicity of thB 

 latter compound in the same way as though the original sol- 

 ution had been diluted to 2CC times its volume. It appears 

 as though the presence of Ca(NG2)2» ^" ^^^^ molecular pro- 

 portion of about 6 to 1, altered the relations between 

 spores and solution so that only a two-hundredth part of 

 the copper nitrate actually present was effective to mod- 

 ify or retard thg germination processes. 



