In 1906 Paul Ehrlich prophesied the role of modern-day pharmaceutical research, predicting that chemists in their laboratories would soon be able to produce substances that would seek out specific disease-causing microorganisms—"magic bullets," as he called them. Ehrlich himself met with signal successes in the emerging fields of serum antitoxins and in chemotherapy. The achievers in this section—both those who elucidated the structures of complex organic molecules and those who used that knowledge to synthesize them—helped create many of the medical "miracles" that improve our quality of life today.