Francisco Torti's Tree of Fevers, 1712. Torti, an Italian physician, was the first to systemically study the medicinal effects of cinchona bark (the source of quinine), also known as Peruvian or Jesuit bark. Intermittent fevers, the branches with bark on the left, responded to cinchona, while continuous fevers, the branches without bark on the right, did not. The intermittent fevers were probably due to malaria, an endemic disease in much of Europe well into the 20th century. #MedEd #MedHist