1921] 
ARMSTRONG—SULPHUR NUTRITION IN THE FUNGI, THIOSULPHATE 277 
of high acidity, and that a reversion of the reaction immediately 
follows. Penicillium cyclopium caused the reversion to take 
place before the disappearance of the sugar, suggesting the 
simultaneous production of hydrogen and hydroxyl ions with the 
hydroxyl ions produced in excess. Chambers (’20) has studied 
some interesting relations of the effect of the concentration of the 
sugar upon the reversion of the reaction by Bacillus coli and 
Bacillus aerogenes. Ayers and Rupp (18) have explained the 
simultaneous production of acid and alkali by B. aerogenes in an 
inorganic medium as due to the production of organic acids from 
the sugar with the subsequent formation of alkaline carbonates 
or bicarbonates from the organic acids. 
The results of the determinations of the hydrogen-ion con- 
centration of the medium at relatively short intervals make it 
apparent that the method of determining the initial and final 
hydrogen-ion concentrations of fungous cultures may not give 
an indication of the changes which have proceeded in the reaction. 
Sporulation was retarded or largely inhibited in the more acid 
solutions. Aspergillus niger produced the greatest acidity and 
sporulated at a higher acidity (e. g., Px 1.7-2.1) than either 
Penicillium or Botrytis. The heavy sporulation of Penicillium 
cyclopium in the solution with an initial Pa 4.2 occurred during 
the rapid reversion of the reaction when the acidity of the solu- 
tion was Pg 3.0 or above. 
CONCLUSIONS 
1. MgSO, Na,S,0, MnSO,, KSH, KHSO,, K,8,0,, KCNS, 
and NH,CNS, in general, have served as favorable sources 
of sulphur, in the order named, for Aspergillus niger, Penicil- 
lium glaucum, and Botrytis cinerea. Meagre growth was obtained 
with K,S. Inhibition of growth occurred for Penicilliwm on 
K,S,0, though this compound was better for Aspergillus, in the 
concentration employed, than KSH or KHSO,. 
2. H,S has been produced except where MnSO,, MgSO,, and 
K,S,0, were used. The production of this compound seems 
unrelated directly to hydrogen-ion concentration, concentration 
of the salt, or relative degree of growth. 
3. In the culture solution, sulphates appear as the chief end 
produet of the action of the above-named fungi on Na, 8,0,, 
