SOME time ago one of us (Gy. N.) published a communication¹ on a nitrogen-fixing micro-organism from the root nodules of Lupinus luteus. By analogy with leghæmoglobin, a red-coloured porphyrin pigment isolated by Virtanen² from root nodules of soya beans, Németh presented a working hypothesis of the hæmoglobin-like structure of his red pigment. Interpretation of ultra-violet spectroscopic measurements¹ seemed at the first glance to support this assumption. Furthermore, Matkovics and Tárnoki³ reported to have isolatedâ whenever in impure stateâ a porphyrin methyl ester from root nodules of Lupinus Iuteus. As forecast by Németh¹ more extensive studies were still needed to support this assumption. We wish now to report on our ultra-violet absorption spectral examinations with pigments from strain Pr-E/3 of Németh, independently of the work by Schneider, and by Matkovics⁶. On the other hand, paper chromatographic investigation of the acidic extracts prepared from this micro-organism has also been carried out.