This was long asserted as probable before Winogradsky showed that the conclusions of M.
As regards the ammonium carbonate accumulating in the soil from the conversion of urea and other sources, we know from Winogradsky's researches that it undergoes oxidation in two stages owing to the activity of the so-called " nitrifying " bacteria (an unfortunate term inasmuch as " nitrification " refers merely to a particular phase of the cycle of changes undergone by nitrogen).
Mintz and others had proved that nitrification was promoted by some organism, when Winogradsky hit on the happy idea of isolating the organism by using gelatinous silica, and so avoiding the difficulties which Warington had shown to exist with the organism in presence of organic nitrogen, owing to its refusal to nitrify on gelatine or other nitrogenous media.
Winogradsky's investigations resulted in the discovery that two kinds of bacteria are concerned in.
Cohn long ago showed that certain glistening particles observed in the cells of Beggiatoa consist of sulphur, and Winogradsky and Beyerinck have shown that a whole series of sulphur bacteria of the genera Thiothrix, Chromatium, Spirillum, Monas, &c., exist, and play important parts in the circulation of this element in nature, e.g.
This iron deposit is not merely mechanical but is due to the physiological activity of the organism which, according to Winogradsky, liberates energy by oxidizing ferrous and ferric oxide in its protoplasm - a view not accepted by H.
amylobacter can ferment cellulose, and the case of mud bacteria which evolve sulphuretted hydrogen below which is utilized by sulphur bacteria above has already been quoted, as also that of Winogradsky's Clostridium III.
Fermentation, &c.: Warington, The Chemical Action of some Micro-organisms (London, 1888); Winogradsky, " Recherches sur les organismes de la nitrification," Ann.