1921] 
ARMSTRONG—SULPHUR NUTRITION IN THE FUNGI, THIOSULPHATE 271 
The produetion of H,S has seemed unrelated to any of the 
factors determined in these experiments, such as hydrogen-ion 
Ory wt 
Ka DE EA ~. 
100 7 SS 
/ 
| 
, 
eo V 4 
40 5 
vA 
20 6 
0 7 
0 4 8 12 16 20 
Days 
Fig. 16. Aspergillus niger on solution of initial Pg 4.1 containing 
magnesium sulphate. 
dry weight. 
hydrogen-ion concentration. 
(The legend above holds for figs. 16-21.) 
concentration, concentration of the salt, relative decomposition 
of the salt, or relative degree of growth. This compound is 
generally produced, but the rather similar conditions under which 
it sometimes fails to occur make it difficult to relate clearly its 
