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Acid hydrolysis of cordycepin yields adenine and cordycepose. Cordycepose (VI) is shown to be a 3-deoxypentose with a branched carbon chain, and cordycepin is shown to be 9-cordyceposidoadenine (IX) .PART I * described the isolation of a crystalline metabolic product, cordycepin, from culture fluids of Cordyceps militaris (Linn.) Link. Analyses of cordycepin and its derivatives indicated a molecular formula C,,H,,O,N, for the former, and preliminary examination revealed that the molecule contains three active hydrogen atoms but no methoxyl, C-methyl or N-methyl groupings.The first indication of the nature of cordycepin was obtained from a consideration of its ultra-violet absorption spectrum which exhibits a well-defined maximum a t 2600 A . (E fi 15,000) in neutral, acid, or alkaline solution. This absorption spectrum is very similar to those of adenine, 9-methyladenine, and adenosine (9-D-ribofuranosidoadenine) (Gulland and Holiday, J., 1936, 768 ; Table I) but substantially different from that of 7-methyladenine.

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A method is described for the determination of the molecular weight of a picrate by an examination of its light absorption in the ultra-violet region of the spectrum. The determination is carried out with approximately 2 mg. of the picrate, the accuracy being of the order of 1 2 % . ETHANOLIC solutions of picric acid exhibit high-intensity absorption between 2000 and 2500 A . , and between 3500 and 4000 A. (figure). Few colourless organic compounds show absorption of appreciable intensity between 3500 and 4000 A. These two facts led us to investigate the possibility of determining molecular weights of bases and hydrocarbons by the measurement of the intensity of light absorption of their picrates within the region 3500-4000 A . By using a Unicam photoelectric spectrophotometer of the compensating-cell type, the light absorption characteristics of a number of picrates were examined. Table I lists the observed intensity of absorption of these picrates at 3800 A . , a wave-length chosen from the high-intensity band of picric acid (3400-4000 A . ) , a t a point remote from the region 2000-3500 A . , in which highintensity absorption is frequently observed in colourless compounds. This choice is to a certain extent arbitrary, similar results to those described being obtained by measurement of the intensity of absorption at other wave-lengths within the high-intensity band of picric acid.