as . 2ee.lr. Pads film exposed by light. The bleck spouts on tue fllm, scid in. “ink, exactly matched the colored spots on the filter paper. ' The irfinitesimally svall cmourtse of material whic: can be detected by this method would have to be increased by 2 thousend or even a million in order to be seen cr wigshed or studded by ordinary chemicel tachnivues, s@id Jr. fink. Conventional chemical studies, including radioiccaine, have been successful in separating the fZodine containizing substences of th: uhzroid into only three fr ctions, he ssid. wnen the thyroids of rats injected with radioiodine were stidied by the new techni..cue utilizing radioautographs of chro@etoprafls, radicactive spots were found as expected at the positions taken on the filter paper bly three known fractions, but inf/addition there vere4 Hole series of uncrpected radioactive spots indicating UnnKnokn conocundse 2 The roast intencively rouioactive of these, according to ur. Fink, had Seen Min sana a pe : : _ tentaviiy idéntifled as mongidotyrostne, a substance each mover has been isolated from thyrcdd. It coinwides exgetly in position em. shope with tho ccLored upot ebtained when a relatively lorge arount of moneisdotyrosine is eaded to the original droplet of thyroid extreacte % The same tecnnique has been uscd Ly the Pinke in pr -lininary studies of the steps in phetosmthgsis, the formation of sugar from carber dieo.ide on planta, a process as.ential to the food supply of the entire world. 4 similar procedure hes also been employed by other reachers in sdudying the oreakdowa in the body of the amino acid lysine, one of the essential building blocks of protiens. Summarizing the uses of the new technique, ur. Fink said: (1) unknown or unexpected compounds cen be detected, (2) the position on the peper fives a clue to what these compounds might be (3) The technijue permits a matching of unknoym with known compounds (4) aif the compounds fail to match, the filter paper is of great assistance in riving an assay precedure evolving steps in purification of the