The modern pharmaceutical industry began with local apothecaries that expanded from their traditional role distributing botanical drugs such as morphine and quinine to wholesale manufacture in the mid-1800s, and from discoveries resulting from applied research. Intentional drug discovery from plants began with the isolation between 1803 and 1805 of morphine - an analgesic and sleep-inducing agent - from opium by the German apothecary assistant Friedrich Sertürner, who named this compound after the Greek god of dreams, Morpheus. By the late 1880s, German dye manufacturers had perfected the purification of individual organic compounds from tar and other mineral sources and had also established rudimentary methods in organic chemical synthesis. The development of synthetic chemical methods allowed scientists to systematically vary the structure of chemical substances, and growth in the emerging science of pharmacology expanded their ability to evaluate the biological effects of these structural changes.