27 



Copper . As was to be expected the effect of Cu(HC2)2 

 upon germination of the spores was found to be widely differ- 

 ent from that of I.'glNOgjg and CaCKOgjg. No germination was ev- 

 er found in concentrations higher than C.0CC06m. and it was 

 only in an occasional culture that one or two spores -vere ob- 

 served producing local swellings at the concentration just 

 mentioned. Local swellings of the spore walls and swollen 

 tubes were frequently found at 0.00004m and at the next low- 

 er concentration used above that, 0.0C0026+m; at O.C0002m 

 germination was about as in distilled water. 



Copper nitrate was combined with Ca(N02)2 at several 

 concentrations of the copper salt well above that at which 

 the latter was non-toxic when used alone. In a series of 

 combinations of O.OOOlra Cu(N02)2 with different concentrat- 

 ions of the calcium salt, ranging from 0.000C3125m to 

 O.C00625m, the spores germinated readilg in those cultures 

 where the concentration of CaCNOg)" was 0.0000625m or higher. 

 With the last named concentration many local swellings were 

 found and also short swollen tubes (see Fig. 2 ) much as in a 

 concentration of 0.O00C4m Cu{N03)2 alone. With the next low- 

 er concentration of the calcium salt C. 00003125m no germin- 

 ation occurred. 



From the above it appears that the toxicity of 

 O.OOClm Cu(N03)2 is so reduced as to be pyhsiologically equi- 

 valent to a 0.0C0C4m solution of the same salt, by the addition 

 to the former solution of five molecules of the CaCNOjIg for 

 every eight molecules of Cu(N03)2 present. The addition of 



