1921] 
ARMSTRONG—SULPHUR NUTRITION IN THE FUNGI, THIOSULPHATE 251 
sulphate content was held constant at practically a .6 per cent 
solution, while the hydrogen-ion concentration was varied from 
an initial Py of 3.0 to 7.1. Increases in the hydrogen-ion con- 
centration of the original medium were obtained by the addition 
Dry wt Cc. 
cgms. Pa lodine 
80 Re “TCE 4 
7 d V 
PA M 
s P t 
| Z 4" 
60 Pa V 8 
/ * 
/ \ 
40 $ 5 \ 12 
0 7 20 
o 4 8 12 16 
Days 
Fig. 2. E cyclopium on solution of initial Pg 4. 2 con- 
taining thiosulphat 
ofN/5 HCl, while the decreases were obtained by the use of N/5 
NaOH. If either of these compounds be added before steri- 
lization, a caramelization and consequently a decided change in 
the medium occurs, so that the following procedure was adopted. 
The solution was mixed en masse for a particular series and 
(50—x) cc. pipetted into flasks of 120 cc. capacity which were 
then sterilized in an autoclave at 15 pounds pressure for 20 
minutes. After cooling, x cc. of sterile acid or alkali were added 
under sterile conditions to each flask which was then allowed to 
