STEINBERG: GROWTH OF ASPERGILLUS NIGER 5 
Reference to figures given for Exps. III and IV indicates that 
the yield concentration curves intersect in both cases at approxi- 
mately 0.075 mg. Zn/L. With this concentration the yields with 
both strains under the conditions employed should be identical 
and equal to about 0.85 gram. 



é 
















S 
m 










Grams Yield 


























































02 06 06 | 
Milligrams Zinc per Liter 
_Fic. 1. For explanation see text. 
The number of concentrations employed was evidently not suf- 
ficient to establish the precise location of the minimum zinc con- 
centration producing the maximum yield, more particularly in 
the case of the Y strain; and, furthermore, a comparison of the 
- yields obtained in this experiment with those obtained in the pre- 
viously cited experiments shows that the organisms are not re- 
acting uniformly to what are intended to be identical cultural 
conditions. This is brought out more conspicuously if we include 
in our consideration the results obtained several months later 
(Exes. VIII and IX). 





OD TN Pe oo ele See pie ect 0.136 gram 0.205 gram 
Ce te ee eae .287 26a 
0.1 nT ek Giapeen re algirig’ aca Sue uo ga oe es C872" 
0.5 = 0543" 0.826 * 
TO Fu Pama ne oor —*: 6.8590" 
5.0 Ore ey aaa 0.963“ CIS 
10.0 7 0.906 “* ie iy & ea 
15.0 Prat i cleat ele e ele sees a ewe n002 0.740." 
20.0 “ge ne O.00r Oa, 
25.0 Tec? Ue irecbieta eee ermcar dig oe Reale «te O45 =" O7s4: 
For these experiments also the yields have been plotted against 
zinc concentrations (TEXT FIG. 2). 
