It is now more than seventy years since Mein announced the discovery in belladonna of an organic base. The discovery was made independently two years later by Geiger and Hesse, who in the same year discovered in stramonium a similar base to which they gave the name daturin, also in henbane another which they called hyoscyamin. It is needless to follow the details of the subsequent investigations which even yet are not complete. Suffice it to say that they have led to the conclusion that the bases discovered in the several mydriatic drugs, belladonna, stramonium, henbane, mandragora, duboisia and scopola, and named at first from these respective drugs, atropin, daturin, hyoscyamin, mandragorin, duboisin and scopolamin, are mixtures chiefly of three or possibly four alkaloids, two of which, atropin and hyoscyamin, are isomeric; the other two, if we adopt the views of O. Hesse, are also isomeric, although differing somewhat in