The 1st part reviews the investigations of the senior author since 1900. The nutrient medium proposed by the author was compared with those of Hellriegel and Crone. The special feature of this medium was the NH4NO3. In the 2nd part the experimental results of the junior author are presented. It is a detailed study of the mutual influence of the different ingredients comprising the Prianishnikov medium. The NH4NO3 gives a characteristic physiological acidity, the NH4 ions being more speedily absorbed. The influence of various plants on the reation of a complete medium containing NaNO3, NH4NO3, or NH4C1, with a small amount of KH2PO4, was qualitatively somewhat similar. On the nitrate media the general tendency for all plants was to neutralize the original acidity of the solution (pH 5.5) it was, however, not so pronounced with buckwheat. In the presence of NH4C1 legumes increased the active acidity to pH 3.9-3.6, at which point they died; grain crops, like oats and corn, brought the pH to 3.3-2.9. Buckwheat tolerated the acidity produced with NH4Cl to a greater extent than all the other plants. For all plants the difference in pH for the media with NH4NO2 and those with NH4C1 was not great within the experimental period of 3 weeks.