[Vor. 8 
242 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
thiosulphate content, growth, and the use of the sugar, a sufficient 
number of flasks were inoculated so that 3 flasks could be removed 
at stated intervals and the several determinations made from 
these cultures. It is impossible to make all the determinations 
throughout from the same flasks, which would be a preferable 
method if convenient, though the results obtained indicate that 
the method employed is satisfactory. 
Hydrogen-ion concentrations were determined 
using the standard solutions as recommended by Clark and Lubs 
(17). As the color produced in the solution necessitated the 
use of a colorimeter, a DuBoscq micro-colorimeter was employed 
of the type and according to the method described by Duggar 
(19). 
4 
ically 
J?) 
T^ 
Ex AL RESULTS 
A. AVAILABILITY OF SOME COMPOUNDS AS SOURCES OF SULPHUR 
The experimental work presented in this paper was in progress 
several years, experiments 1-15 having been completed during 
the period 1915-1917 at the University of Wisconsin and the 
remainder of the experiments at the Missouri Botanical Garden 
during the sessions 1919-20 and 1920-21. Several of the solu- 
tions of the first 15 experiments are the same as those used by 
Kossowiez and Loew and Kossowiez and Gróller. Only 15 of the 
32 experiments performed during the first period of the work are 
presented, the results obtained being in more or less general agree- 
ment throughout. The cultures were placed in a large constant 
temperature dark room with a variation of from 22 to 25? C. The 
fungi have been designated in the tables by abbreviations as, 
Aspergillus niger, A. nig.; Penicillium glaucum, P. gl.; Penicillium 
cyclopium, P. cycl.; and Botrytis cinerea, B. cin. 
The extent of the darkening of the lead acetate paper is taken 
as the criterion of H,S production which is expressed roughly 
by the figures 0, 1, 2, 3, 4. An attempt is made to give a general 
indication of the relative spore production by the use of the same 
figures. The tabulated data as to the presence of sulphates is 
given by the plus and minus signs without any attempt to express 
the relative production of such compounds. This system of 
notation appears in all the tables. 
The nutrient solution used to obtain the results given in table 
