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ROBERT AARON STEINBERG 
fluencing the organic processes at another stage, or in another way, may 
bring about the same result. 
The effect of increased acidity, and of decreased acidity as well, of the 
Pfeffer nutrient solution are indicated in the following experiments. In- 
creased acidity of the nutrient solution was brought about through the 
addition of different free concentrated acids immediately after sterilization. 
In order to obtain cultures of lower acidity than the Pfeffer solution, free 
alkali was added. In all cases full precautions were taken for the exclusion 
of zinc, etc. 
19. The effect of increasing the acidity of the culture medium. 
Strain W, 5 
Control 
H3PO4 (Kahlb. kryst.) 
0.133 g. 
O.I cc./flask 
0.279 g 
0.124 
0.2 
0.302 
0.146 
0.3 
0.307 
0.140 
0.4 
0.232 
0.I2I 
0.5 
0.178 
0.133 
20. The effect of an increase or of a decrease in acidity of the culture medium. 
Strain W, 6 
Control K0H(5:6)* 
0.107 g- O.I cc./flask 0.109 g. 
0.126 0.2 0.055 
0.126 0.3-0.5 No growth 
0.120 
NH4OH (Sp. Gr. 0.90) 
HNO3 (Sp. Gr. 1.42) 
O.I cc./flask 
0.2 
0.3 
0.4-0.5 
0.065 g. 
0.030 
0.023 
No growth. 
0.1 cc./flask 
0.2-0.5 
0.200 g. 
No growth. 
HCl (Sp. Gr. 1. 18) 
H2SO4 (Sp. Gr. 1.84) 
O.I cc./flask 
0.2 
0.3 
0.4-0.5 
0.291 g. 
0.129 
0.106 
No growth 
0.1-0.5 cc./flask 
No growth. 
The hyphae in the cultures to which KOH or NH4OH was added were watery and 
translucent in appearance. Sporulation in these cultures was very good. In those to 
which HNO3 or HCl was added the hyphae were opaque, the membranes wrinkled, and 
spore formation was retarded. 
* Baker's "Analysed": NH4OH, KOH, HNO3, HCl, Ba(0H)2, tartaric acid. Baker's 
"U.S. P.": acetic acid. Baker's "special": oxalic acid, H2SO4. Kahlbaum: H3PO4 
kryst. 
