[Vor. 8 
278 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
H,5 is generally produced, molecular sulphur in visible quantity 
not infrequently appears, the tetrathionate has been identified 
in certain cases, and in the hyphae globules of sulphur sometimes 
occur. 
4. The ratio of thiosulphate decomposition to growth is not a 
constant in all eases for Aspergillus niger, Penicillium cyclopium, 
and Botrytis cinerea, though in the 12 series of cultures here re- 
ported upon such a constant relation does appear with one or 
more of the fungi in 8 of the series. The usual growth range of 
hydrogen-ion concentration does not appear to be a limiting factor 
in the efficiency of the thiosulphate as a source of sulphur for 
these fungi. 
5. In a modified Pfeffer's solution the disappearance of the 
sugar, within the limits determined, marks the point of the re- 
version of reaction for Aspergillus niger. Penicillium cyclopium, 
on the other hand, may cause a reversion of the reaction with 
sugar present in the solution. 
6. Since it has been established that reversion of the reaction 
may occur, it is clear that the true course of the changes which 
have occurred may not be obtained merely by a determination of 
the initial and final hydrogen-ion concentrations of the fungous 
cultures. 
The writer wishes to express his appreciation of the invaluable 
suggestions and criticisms of Dr. B. M. Duggar in the later in- 
vestigations which are the subject of much of this paper. Thanks 
are extended to Dr. J. B. Overton, of the Department of Botany 
of the University of Wisconsin, for helpful direction and advice 
in the early progress of this work. "Thanks are also due Dr. 
George T. Moore for the privileges and facilities of the Missouri 
Botanical Garden. 
Graduate Laboratery, Missouri Botanical Garden. 
BIBLIOGRAPHY 
Ayers, S. H., and Rupp, P. ('18). Simultaneous acid and alkaline bacterial fer- 
mentation from dextrose and the salts of organic acids, respectively. Jour. 
Infect. Dis. X 188-216. f. 1-11. 1918. 
Beijerinck, M. W. (95). Ueber Spirillum desulfuricans als Ursache von Sulfat 
reduktion. Centralbl. f. Bakt. II. 1: 1-9. 1895. 
