Ajacine was first isolated from the seeds of Delphinium ajacis by Keller and Volker (Awh. Pharm., 1913, 251, 209), who assigned to it the formula C15H,10,N,H,0. Recently, Hunter (Pharm. J., 1943, 150, 82) proposed the formula C3,H,,0,N,,2H,0. As it was thought that ajacine might be closely related to lycaconitine from Aconitum Zycoctonum, which Schulze and Bierling (Arch. Pharm., 1913, 251, 8) showed to be succinylanthranoyl-lycoctonine, and to methyllycaconitine from D. elatum, which Goodson (J., 1943, 139) found to be methylsuccinylanthranoyl-lycoctonine, it has been submitted to hydrolysis. Alkaline hydrolysis gives acetylanthranilic acid and lycoctonine according to the equation C3,H,,0,N2 + H,O = C,,H,,O,N + CQHoO3N and acid hydrolysis yields acetic acid and anthranoyl-lycoctonine: C3,H4,0,N2 + H,O = CH,CO,H + C3,H,,0,N2. From this it follows that ajacine is acetylanthranoyl-lycoctonine and has the empirical formula C3,H,,0,N2,2H,0.