The amino acids in hydrolyzed and unhydrolyzed tissues of the slime mold, Dictyostelium discoideum, were determined by means of 2 -dimensional ascending paper chromatography. Analyses were made on 4 stages of development[long dash]migrating pseudoplasmodium, pre-culmination, culmination, and mature sorocarp. Unhydrolyzed tissue contained the leucines, methionine, tyrosine, alanine, threonine, glycine, serine, glutamic acid, aspartic acid, cystine, and 7 unidentified spots, presumably simple peptides. Not all these spots were present in all tested stages. Hydrolyzed tissue contained in addition to amino acids already mentioned, phenylalanine, proline, histidine, asparagine, and one unknown spot. All tested stages were identical. The postulate is presented that glutamic acid (and possibly also to a lesser extent aspartic acid, alanine, serine, and cysteine) through deamination may enter the Krebs cycle and form a link between protein and carbohydrate metabolism, the change in balance between protein and carbohydrate being one of the most prominent features of differentiation in this organism.