CHEMICAL STIMULATION OF GROWTH OF ASPERGILLUS NIGER 363 
I Mg-. Fe2(S04)3/Flask 
HsPO^/FIask 
Yield 
Ph 
Sporulation 
0.2 CC. 
0.134 g. 
2-3 
Excellent 
0.2 
0.128 
2-3 
Excellent 
0.4 
O.IIO 
2-3 
Sterile 
0.1 Mg. Zn/L 
H3P04/Flask 
Yield 
Ph 
Sporulation 
0.2 CC. 
0.594 g. 
1-2 
Sterile 
0.3 
0.552 
1-2 
Sterile 
0.4 
0.337 
1-2 
Sterile 
0.2 Cc. H3P04/Flask 
Fe2(S04)3/Flask 
Yield 
Ph 
Sporulation 
0.5 mg. 
0.122 g. 
2-3 
Excellent 
I.O 
0.090 
2-3 
5.0 
0.172 
2-3 
Sterile 
20.0 
0.845 
2-3 
0.2 Cc. H3P04/Flask 
Mg. Zn/L 
Yield 
Ph 
Sporulation 
0.075 
0.654 g. 
1-2 
Sterile 
0.2 
0.477 
1-2 
0.5 
0.456 
1-2 
PfefFer Solution 
Control 
Mg. Zn/L 
Yield 
Ph 
Sporulation 
• 
0 
0.253 g. 
3-4 
Excellent 
I 
0.895 
1-2 
Good 
10 
0.909 
1-2 
25 
0.972 
1-2 
+ 1% Ca(N03)2 +0.1 Cc.NH40H/Flask 
Mg. Zn/L 
Yield 
Ph 
Sporulation 
0 
0.398 g. 
3-4 
Excellent 
I 
0.850 
1-2 
Good 
10 
0.887 
1-2 
25 
0.787 
1-2 
The Ca(N03)2 used was the Baker's ''Analysed." In both experiments 
34 and 35 as well as in experiment 36 only 15 g. CaCOs per liter were used 
in effecting the purification. 
Here again it is shown that the addition of both zinc and iron is necessary 
in order to obtain marked increases when the treated Pfeffer solution is used. 
Either alone in much higher concentration is apparently ineffective, growth 
being limited by the absence of the other. Nevertheless, with very high 
iron concentrations a marked acceleration of growth occurs. The same is 
also true for iron in acidified culture (0.2 cc. H3PO4 and 20 mg. Fe2(S04)3 
per flask) as well as for zinc only. It should be emphasized that both the 
