50 



Zinc. Zinc nitrate alone and in combination with 

 the nitraL3S of calcium and magnesium was studied in much 

 the same way as were the nitrates of copper and lead. Zinc 

 nitrate inhibited germination in C.25m concentration. Many 

 local swellings of the spore walls v;ere found in concentra- 

 tions of C.C8m and 0.04ra, while local swellings and short 

 tubes were present in concentrations of O.GCSm and C.CC4m. 

 Normal germination occurred in a concentration of C.CC2m. 

 Combinations of Zn(NC3)2 with Ca(NG3)2 and Ivlg(NG2)2 v^ere 

 tested using a concentration of Q.C4m Zn(NC2)2. In these 

 combinations the calcium salt was employed in concentratiai s 

 ranging from C.O0C125m to C.02ra. Some normal germination 

 occurred with all concentrations of Ca(N03)2 below and inc- 

 luding that of C.CC05m, but none was observed in the mix- 

 ture containing a. C. 000125m concentration of this salt. It 

 thus appears that. normal germination of these spores in a 

 0.04 Zn(K02) solution may be brought about by the addit- 

 ion of Ca(RC3)2 in the proportion of one molecule of this 

 to every 80 molecules of z.n(NO )2 present in the solution. 



The concentrations of Mg(NC3)2 which were employed 

 in these combinations with the 0.04m solution of Zn(NC3)2 

 ranged from 0.00C25m to O.C2 5m. Here it was found that no 

 normal germination occurred until the magnesium salt 

 reached a concentration in the mixture of C.C025m. This 

 means that to produce any normal germination in the 

 Zn(NC3)2 solution here used, by addition thereto of 

 l!g{NC3)2 , it is necessary to add one molecule of the 



