82 



LON A. HAWKINS 



No direct evidence was obtained as to whether or not zinc nitrate enters 

 the spores. 



Aluminum. 



Aluminum nitrate was used at certain concentrations, both alone and in 

 combination with magnesium and calcium nitrates. Series were carried 

 out, and several times repeated, including the combinations and concentra- 

 tions which are presented in table III. 



TABLE III 



Concentration of Al(NO 3 ) 3 

 molecular 



Concentration of Mg(NO,) 2 



or of Ca(NO 3 ) 2 , 



molecular 



In none of the cultures with A1(NO 3 ) 3 did the addition of either 

 Mg(NO 3 ) 2 or Ca(NO 3 ) 2 bring about any alteration at all in the behavior 

 of the spores. Although many other proportions of these pairs of salts 

 might have been tried, it appears probable that, if either the calcium or 

 magnesium salt, at any concentration, exerts any influence upon the toxicity 

 of A1(NO 3 ) 3 , in any concentration, some evidence in this direction would 

 have been obtained from the experiments which were carried out. This 

 seems still more probable from the fact that different concentrations of 

 the aluminum salt alone produced markedly different effects upon the 

 activities of the spores, a matter which will now receive attention. 



In the highest concentration of A1(NO 3 ) 3 used in the combinations, 

 namely 0.0045111, only a few local swellings of the spores were observed. 

 A blackening of half of the spore was frequently found here (fig. 6). No 

 normal germination occurred in this solution. In the two lowest concen- 

 trations of A1(NO 3 ) 3 (0.005111 and 0.00025111) however, much of the germ- 

 ination was normal. Aluminum nitrate appears to influence the form of 

 germination occurring in these spores, with much the same results as have 

 been described for cultures poisoned with Pb(NO 3 ) 2 . The types of renewed 



