[Vor. 8 
260 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
these cultures, though later experiments in this report will show 
that Penicillium may cause a reversion of the reaction before the 
sugar has disappeared. 
Dry wi. Ge. 
coms Pa Lod,ne 
a— am em — en 1 o 
prs 
A 
J aa — e d 
2 ‘Words 
100 Py 3 
/ f 
/ 
^ d 
80 L / 3 
At -— 
WE. 
60 7 | 7 ii 14 
40 N 5 25 
on i 
20 4 19 
/ / 
0 4 8 12 16 20 
Days 
Fig. 7. Aspergillus niger on solution of initial Pa 4.5 containing 
thiosulphate. 
C. GROWTH AND HYDROGEN-ION CONCENTRATION WITH MgSO, 
SUBSTITUTED FOR Na.8,0; AS A SOURCE OF SULPHUR 
The basic solution in which equi-molecular weight substitu- 
tions as Na,S,0, were employed in the 4 preceding experiments 
was now used with MgSO, as the source of sulphur. To keep the 
