Duboisia Leichhardtii has been shown to contain hyoscyamine and small amounts of l-hyoscine, dl-hyoscine, norhyoscyamine, and a new alkaloid provisionally named "Base D." The last was similar to but not identical with isovaleryltropëine, the hydrobromide of which has now been synthesised. The drug has been compared botanically with the D. myoporoides found not to contain hyoscyamine by Barger, Martin, and Mitchell (J., 1937, 1820; 1938, 1685). It is suggested that at least two distinct types of Duboisia have appeared in commerce.