[Vor. 8 
276 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
In experiments 16-19 inclusive, in which the thiosulphate was 
used as a source of sulphur, the ratio of thiosulphate decomposed 
to growth is not a constant in all cases, but the constant rela- 
tion does appear in 8 of 12 sets of cultures as shown in figs. 
4,5, and 6. The hydrogen-ion concentration of the medium does 
not appear to be a limiting factor in the efficiency of the use 
of the thiosulphate. 
Ory wt 
c ; 
ióo Pa 
gat, 
fy” 
60 
// 
8 12 16 20 
Days 
Fig. 21. Botrytis cinerea on solution of initial Pa 5.5 containing 
magnesium sulphate. 
Reversions of the reaction from the more acid condition to- 
wards neutrality were observed with both Aspergillus and Peni- 
cillium. From the results of experiments 20 and 21 it is seen that 
Aspergillus caused a rapid decomposition of the sugar, that the 
total disappearance of the sugar is accompanied by the production 
