Paul Ehrlich: the Nobel Prize in physiology or medicine 1908.

We wish to commemorate Paul Ehrlich on the centennial of his being awarded the Nobel Prize in Physiology or Medicine in 1908. His studies are now considered as milestones in immunology: the morphology of leukocytes; his side-chain theory where he defined the cellular receptor for first time; and his clarification of the difference between serum therapy and chemotherapy. Ehrlich also invented the first chemotherapeutic drug: compound 606, or Salvarsan. We have used some original documents from the Royal Society of London, where Ehrlich was a fellow, and from Leipzig University, where he took a degree in medicine.