History of malaria and brain which are the most constant post-mortem indications of chronic malaria infection. He related the prevalence of malaria in swampy areas to the presence of flies and recommended swamp drainage to prevent it. In the nineteenth century, the first drugs were developed to treat malaria and parasites were first identified as its source. French chemist Pierre Joseph Pelletier and French pharmacist Joseph Bienaimé Caventou separated in 1820 the alkaloids cinchonine and quinine from powdered fever tree bark, allowing for the creation of standardized doses of the active ingredients. Prior to 1820, the bark was simply dried, ground to a
Tonic (music) so on. In western European tonal music (key-based music) of the 18th and 19th centuries, the tonic center was the most important of all the different tone centers which a composer used in a piece of music, with most pieces beginning and ending on the tonic, usually modulating to the dominant (the fifth above the tonic, or the fourth note down from the tonic) in between. Two parallel keys have the same tonic. For example, in both C major and C minor, the tonic is C. However, relative keys (two different scales that share a key signature) have different tonics.