In this part the experimental results on the changes in litmus milk, gelatine liquefaction, and nitrate reduction are described. Litmus milk : According to serum zone and change in reaction, the nodule bacteria are divided into three groups : Reaction alkaline and serum zone positive. …Strains form pea-, clover-, bean-, and cowpea-group, Sesbania, Astragalus, Sophora, Amorpha, Caragana, Robina, Vicia (nipponica). Reaction alkaline and serum zone negative. …Strains form alfalfa-, lupine-, soybean-, and cowpea-group, Styphnolobium, Indigofera. Reaction acid and serum zone positive. …Strains form alfalfa-, soybean-, and cowpea-group, Mimosa, Leucoena, Dalea, Lotus (?) And it will be seen in the above grouping that the rhyzobial strains in one inoculation group or even from one plant are not always found in the same group. Gelatine liquefaction : The yeast water mannital gelatine as will as nutrient gelatine were used as test media, because many strains of rhyzobia were unable to grow on the latter. Few strains liquefy gelatine, although the majority does not. Most strains of alfalfa bacteria and some of pea-, soybean-, and cowpea-bacteria are included in the former. Nitrate reduction : Not all strains of rhizobia are able to reduce nitrate in the nitrate yeast water mannitol medium. Few strains of bean- and cowpea-group, and strains from Astragalus and Amorpha seem to be unable to reduce nitrate. Nitrite accumulation varies, depending upon the strains of rhizobia. Many strains of alfalfa, two of clover, and and one of cowpea group, and strains from Mimosa, Leucoena, and Sophora accumulate appreciable amounts of nitrite, whereas some strains of soybean-, and cowpea-group and strains from Sesbania form no nitrite, although they are all strong nitrate reducers.