The introduction of the s-triazine ring into the amino group of arsanilic acid enhances the trypanocidal and spirochetocidal properties of this compound, provided that at least one unsubstituted amino group is attached to a carbon atom of the triazine ring. The optimum effect is obtained in p-(2,4-diamino - s - triazinyl - 6) - aminophenylarsonic acid. The corresponding arsinoxide and arseno compound are described. In a study of the constituents of the Chinese drug Fritillaria roylei (Pei-Mu), further analyses of the known alkaloids peimine and peiminine indicate that the formulas should be revised to C27H45O3N and C25H41O3N, respectively. In addition to these alkaloids, the author has isolated from the drug a new neutral principle of the formula C26H44O3 or C27H46O3 for which the name propeimin is suggested. Propeimin yields a C19-ketone on oxidation and is cleaved by hydrochloric acid to a C19- C21 product. It is suggested that the alkaloids of Pei-Mu may be related to known steroid alkaloids and propeimin to the steroid sapogenins.