Casein was hydrolysed with sulphuric acid under pressure and the hydrolysate was oxidized and nitrated by a mixture of sulphuric acid and potassium nitrate. After decolorization and neutralization to pH 4, the residue was removed by filtration.After adjusting the filtrate to pH 6.8 and supplementing it with tryp-tophane, cystine, methionine, and tyrosine, it was used as the source of amino acids ill the preparation of the medium for the microbiological assay of phenyl-aianine with Lactobacillus ardbinosus 17-5 as test microorganism.The standard curve shows that the medium is almost free from active phenyl-alanine, for blank values are of the same magnitude as those of a synthetic medium.Increasing the quantity of nitrated casein hydrolysate from 8 g. to 10 g. doesnot cause any difference in acid production. Further supplementation of themedium with fustidine, arginine, and lysine is also without effect.The results obtained by analyses of several foods with the present medium and the findings of Sauberlich and Baumann (1946), and Schweigert (1944) are in

The eight essential amino acid contents of nineteen legumes and cereals of different varieties have been determined with the microbiological methods The methionine and lysine contents of cereals are in general lower than that of animal products. However, the methionine in spiked millet (糜子米) and in panicled millet (小米) and lysine in buck wheat (荞麦) are high. Methionine, tryptophane and isoleucine of the legumes are in general lower than those of the animal products.Past dietary surveys have been re-examined in the light of these analytical results, and a more accurate estimate of the nutritional status of the population, with respect to protein is thereby available.