336 
ROBERT AARON STEINBERG 
Results 
I. The influence of a zinc glass (Jena) on the yield [Reproduced from (64)]. 
MgS04.7H20 (Kahlb.) Room temperature (18-23° C). Period of growth tfen days. 
Jena 
Kavalier 
Bohemian 
Py 
rex 
No Zinc 
10 Mg. Zn/L 
No Zinc 
10 Mg. Zn/L 
No Zinc 
10 Mg. Zn/L 
0.989 g. 
0.980 g. 
0.270 g. 
0.924 g. 
0.319 g. 
0.940 g. 
0.958 
0.940 
0.299 
0.943 
0.248 
0.980 
0.919 
0.988 
0.285 
0.886 
0.306 
0.917 
0.933 
1.005 
0.300 
0.947 
0.252 
0.952 
0.953 
1.022 
0.361 
1. 017 
0.309 
0.997 
0.950 
0.987 
0.301 
0.943 
0.287 
0.957 
2. The influence of a zinc glass (Jena) on the comparative yield of two strains of A. niger 
(W and Y). 
MgS04.7H20 (Kahlb.) 
Strain W, Transfer i 
Pyrex 
Jena 
Pyrex 
Jena 
No Zinc 
o.oi Mg. Zn/L 
No Zinc 
No Zinc 
o.oi Mg. Zn/L 
No Zinc 
0.302 g. 
0.602 g. 
0.805 g- 
0.516 g. 
0.806 g. 
0.763 g. 
0.265 
0.578 • 
0.741 
0.535 
0.830 
0.747 
0.339 
0.562 
0.810 
0.546 
0.843 
0.785 
0.330 
0.528 
0.786 
0.409 
0.694 
0.750 
0.335 
0.554 
O.81I 
0.393 
0.732 
0.787 
0.317 
0.565 
0.791 
0.480 
0.781 
0.766 
Strain Y, Transfer i 
In Jena glass, it will be noted (experiments i, 2) that the maximum 
growth occurs whether zinc is added or not. 
The following experiment reproduced from a former publication (64) 
will also show that the method used in cleaning the flasks is entirely satis- 
factory. The flasks used for the cultures in the second column were 
3. On the efficiency of the method for cleaning the cultural flasks. 
MgS04.7H20 (Kahlb). Pyrex flasks. , 
Flasks Reserved for Zinc-free Flasks Reserved for Zinc 
Cultures Cultures 
* 0.924 g. 0.283 g. 
0.336 0.265 
0.321. 0.313 
0.328 0.341 
0.355 0.352 
0.335 0.31 1 
* An accidental zinc culture. In some cases due to the accidental introduction of zinc, 
in a few cases to the unintentional use of Jena flasks, 
previous to this experiment used three consecutive times for cultures con- 
taining 10 Zn/L and were cleaned as usual. 
