1921] 
ARMSTRONG—SULPHUR NUTRITION IN THE FUNGI, THIOSULPHATE 269 
the reversion becoming apparent in cultures supporting Asper- 
gillus after the seventh day, when sugar was no longer present; 
while the reversion with Penicillium occurred at the same period, 
though sugar was present until after the twelfth day. The change 
in reaction for Aspergillus was from Py 1.5 to 2.0 and for 'Peni- 
cillum from P, 4.1 to 5.1. 
Dry wt P Cs. 
cgr H Jodine 
O 
EE 
60 Sf 10 
i 
: NS 
40 / Jini 14 
e Kites UR 
t - uu s D. 
/ £ j 6 
20 18 
2 "n 
/ 7 De eee 
0 7 22 
0 4 8 12 16 
Days 
Fig. 14. Penicillium cyclopium on solution of initial Pa 7.1 con- 
taining thiosulphate. 
No H,S was produced from any culture where magnesium 
sulphate served as a source of sulphur. 
DISCUSSION 
In all the cultures with Na,S,0, as a source of sulphur, sul- 
phates appear as the chief end product of the action of the fungus 
