Polarised light micrograph of cinchonidine (C19H22N2O) which is one of the quinine group of alkaloids. It is a white crystalline substance with a bitter taste and properties similar to, but less potent than, quinine. In 1633 an Augustinian monk in Peru wrote about the powder from the bark of the fever tree' being used in a beverage to cure the fevers. In 1638 the Jesuits are reported to have used quina bark to cure the Countess of Chinchon, wife of the Viceroy of Peru, of her fevers (malaria). The Countess's nickname was la Chinchona' and the tree species is now known as Chinchona. Quinine, quinidine, and chinchonine (cinchonidine) can be extracted from the bark. Magnification: x27 at 10cm wide.