In addition to histology, Paul Ehrlich made significant contributions to immunology and chemotherapy. He was one of the pioneers in the study of the immune system and its role in defending against diseases. His work on the side-chain theory of immunity was groundbreaking and influenced future research in immunology. In chemotherapy, Ehrlich's search for a "magic bullet" led to the discovery of the first effective treatment for syphilis, called Salvarsan.
