SULPHIDE PRODUCING ORGANISMS 
425 
Petri and Maassen 6 are the strongest advocates of the theory of the formation 
of the sulphide of hydrogen through the action of nascent hydrogen. In support of 
their view they mention the extensive reducing processes occurring through the 
agency of bacteria, e.g., reduction of nitrates to nitrites, to ammonia ; the decoloniza- 
tion of litmus and indigo ; the reduction of ferric- to ferrous-salts, and invert sugar 
to mannite. They assert that they have been able to derive sulphide of hydrogen 
through the action of nascent hydrogen upon all sulphur compounds which yield it, 
through the activity of bacteria ; and that sulphur compounds which have not yielded 
their sulphur to nascent hydrogen, in their experiments, have not yielded it either 
to the action of bacteria. Yet it seems scarcely justifiable to conclude that sulphide 
of hydrogen is therefore formed, in general, through the action of nascent hydrogen 
as such. 
The reduction processes of bacteria are probably very complex, and can well be 
conceived of as proceeding quite independently of nascent hydrogen. 
The fact that a number of sulphur compounds yield their sulphur neither to 
nascent hydrogen nor to bacterial action does not prove that, in some other sulphur 
compounds, from which bacteria are able to produce sulphide of hydrogen, they do 
so through the selective energy of nascent hydrogen as such, even though nascent 
hydrogen be capable of effecting the combination ; for the union of sulphur and 
hydrogen can be regarded as occurring in other ways through energy imparted by the 
living organisms. It has been observed by Winogradsky 10 and others' 2 that certain 
fungi are capable of taking up hydrogen sulphide in large quantity, separating the 
sulphur from the hydrogen and oxidizing it. Just how these organisms are capable 
of dissociating the hydrogen from the sulphur, and of adding oxygen to the sulphur, 
would be difficult to say. It would also be difficult to say just how an organism can 
effect the chemical union of hydrogen and sulphur. 
Beijerinck 9 has isolated an anaerobic organism, which operates, he believes, in 
the depths of polluted waters, and which is capable of reducing calcium sulphate 
directly ; a process which nascent hydrogen is incapable of accomplishing. 
It may be that nascent hydrogen plays a more or less important part in the 
production of sulphide of hydrogen. On the other hand, as already indicated, other 
factors whose nature we do not understand, may operate without its assistance. 
In addition to the formation of sulphide of hydrogen from proteid, sulphur and 
lower sulphur salts, may be mentioned a process regarded as occurring in nature, 
which has been investigated by Hoppe-Seyler 11 and others, viz., the fermentation 
of cellulose with the formation of equal parts of hydrogen and methane. According 
to Hoppe-Seyler, the marsh gas reacts at once with calcium sulphate, if present, 
according to the equation. 
CH + + CaS0 4 = H 2 S + CaCO, + H.O 
