The bark of Medicosma cunninghamii Hook. f. contains approximately 0.06 per cent. of an alkaloid C17H15O3N which has been named medicosmine and shown to be a 2,3-furoquinoline with a dimethylpyran ring fused in either the 5,6- or 6,7-positions (III or IV). It has been degraded to acetone, acetaldehyde, and a phenol which when methylated and oxidized gives 6-methoxy-4-hydroxy-1-methyl-2-quinolone, and 6- and 7-methoxy-4-hydroxy-1-methyl-2-quinolones have been synthesized for comparison. A dihydropyrano-4-methoxy -3-ethyl-2-quinoone is formed by hydrogenolysis of the furane ring. Further examples are reported of the preparation of isatins from 3-nitroso-2,4- dihydroxyquinolines. © 1953, CSIRO. All rights reserved.