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A plate assay technique for the vitamin B, complex has been developed using Saccharomyces carlsbergensis. For the complete u tilisation of pyridoxamine in the plate assay, tryptophan appears to be an essential metabolite for the organism. Indications are also given that a fourth, hitherto unknown, factor of the B, complex may be present in certain yeasts.

IN a recent publication1 it was shown that, by certain modifications of the original method of Stokes, Larson, Woodward and Foster2 in which Neurospora sitophila was used, a satisfactory degree of accuracy could be obtained for the assay of the vitamin B6 complex in yeast and certain other foodstuffs. Unfortunately, the incubation period for the mould is 5 days, which entails considerable delay in obtaining the assay results. The turbidimetric method of Atkin, Schultz, Williams and F re~,~ using Snccharomyces carlsbergensis, has the advantage of a short …