The auther intended to study which of ammoniacal, nitrous and nitric nitrogen is most easily utilized by the rhizobia and whether nitrous and nitric nitrogen are directly assimilated or after being reduced. Experiments were made on the soybean nodule bacteria with the synthetic media as well as the yeast water media in presence of these inorganic nitrogen alone or by two, . by determining nitrogen at intervals. In nitrate and in nitrite cultures, the organisms attacked them without a quantitative corresponding increase in the organic or ammoniacal nitrogen, that is, there was a loss of nitrogen. In nitrate (or nitrite) ammonium cultures, it seemed that all of the nitric (or nitrous) nitrogen were lost out of the media. Thus, the reduction of nitrous of nitric nitrogen was not always referred to as the transformation of them in the proccss of their assimilation.