901 
flora which encloses the chalk and sulfur, and where at last many 
infusoria and monads, that feed on the bacteria, may be observed. 
As said the organic matter of the bacterial bodies must here be 
formed from the carbonic acid, whilst the required chemical energy is 
produced by the oxidation of the sulfur. Consequently this is a case 
of chemosynthesis and no other analogous process is known which 
produces organic substance in a simpler and more profuse way. *) 
By decanting and renovating the saltpetre solution as soon as the 
evolution of gas diminishes, the activity returns. ?) This being repeated 
a few times the precipitate changes into a slimy mass, so rich in 
slime-forming bacteria that at heating on a platinum plate in the 
Bunsen burner carbon is separated. With concentrated sulfuric acid 
carbonisation is also easily demonstrated. As the rate of nitrogen of 
this slime is less than 3°/,, it must chiefly consist of wall substance, 
which is evidently the chief product of the chemosynthesis.*) It 
results from the carbonie acid after the same formula as the starch 
in the chlorophyll granules by photosynthesis, thus 
_6CO, +5 H,0 = CHO, + 60, 
so that oxygen is set free, which explains the ready course of the 
process in a closed bottle, when considering that all denitrifying 
bacteria require a little free oxygen. 
Just as the organic denitrification, that with sulfur may as well 
take place in the dark as in the light. After pasteurisation no sulfur- 
denitrification or oxydation is observed. 
The quantitative estimation of the carbon fixed by chemosynthesis 
was made as follows. The sediment was treated with hydrochloric 
acid and later with alkali to remove the chalk and the sulfur, 
whereby certainly a great portion of the organic substance is lost. 
In the remaining precipitate, which still contains gypsum, the organic 
matter was determined as carbonic acid after the method of Hmrzrr.p- 
') It is true that chemosynthesis at the oxidation of hydrogen in presence of 
carbonic acid and soil, described by NikLEwsky and LEBEDEFF, is as productive 
in organic substance, but the experiment is less simple. 
*) Addition of soda instead of decantation and renovation, also acts favourably. 
Evidently the dissolved sulfuric acid is difficultly neutralised by the chalk of the 
precipitate. 
*) See also: A. J. Leseperr, Ueber die Assimilation des Kohlenstoffs durch 
Wasserstoff-oxydierenden Bakterién. Berichte d. Deutschen Botan. Gesellsch. Bd 27, 
Pag 598, 1909. He says that the bacterium can oxidise hydrogen in absence of 
CO,; this, however, is manifestly erroneous. Nor does he take into consideration 
the oxygen produced at the denitrification by the hydrogen of the saltpetre, used 
by him as source of nitrogen. His fear that by using ammonsalts nitrification 
would follow, is under these conditions unfounded. 
