Using the fluid media containing any one member out of eleven amino acids and nicotic acid or certain combination of them, the author studied the effect of these nitrogen sources on the growth of some species of Staphylococcus, Salmonella and Shigella, that were the departmental stock of author's laboratory. And the following results were obtained. 1) It was found that Staph. aureus and Staph. albus required many species of amino nitrogen and growth factors. The author failed to culture them in the media described above, for the lack of some required components for their growth. 2) Sal. enteritidis and Sal. typhi murium could grow sufficiently in the media containing merely ammonium nitrogen, but the extra addition of cystine to the media showed the marked increase of growth. 3) The growth of Sal. typhi 57 S and R were accelerated by the addition of sulfur containing amino acids, cystine and methionine, And also glutamic acid and aspartic acid could serve to these micro-organisms as nitrogen source. Sal. paratyphi A reqired cystine as the essential amino acid, but in the case of Sal. paratyphi B and C it was effective to add glutamic acid and phenylalanine to the basal media. 4) Nicotinic acid seved as the essential factor to the Shigella species, Shigella sonnei and Shgella flexneri 2a; in addition, aspartic acid showed the stimulation for growth.