During the Middle Ages medicinal herbs were cultivated by friars in monasterygardens. Moreover they were often collected and dispensed by some women (“geneesjoffers”). In the sixteenth century pharmacists made their first appearance. In some towns, such as Leyden, the apothecaries gathered into guilds. The pharmacists’ guilds exercised supervision of the chemist’s shops and examined apprentices before admitting them into their guild. In Amsterdam the supervision was exercised by the collegium medicum, which drew op a municipal pharmacopoea in 1616 at the proposal of Nic. Tulp.