The bacteria of Nebraska soil, with special reference to the fixation of nitrogen, ammonification, denitrification in non-protein media, including observations on the reduction of nitrates by soil bacteria in general

This work was undertaken with the idea of ascertaining if possible, some of the many chemical changes taking place through the action of bacteria indigenous to Nebraska soil. The fixation of nitrogen was first observed by M. Berthelot in 1885. He subsequently was able to prove that this pheno- menon is not brought about exclusively by a purely chemical process, but is due to the activity of micro-organisms. The discovery of an anaerobic organism by S. Winogradsky in 1893, Clostridium pasteurianum, which he found fixed from 2.5 to 3 mg of nitrogen per gram of dextrose consumed, marked the first advance along this important line. Recent observers have added a few organisms to the list, Beyerinck, Löhnis and Lipman having labored successfully in this field