Paul Karrer was born in Moscow, Russia, on April 21, 1889, the son of Julie Lerch Karrer and Paul Karrer, a Swiss dentist who was practicing in Russia. At three years of age Karrer and his family returned to Switzerland. In 1908 he entered the University of Zürich, ultimately studying chemistry under Alfred Werner, whose work on the linkage of atoms in molecules won him the Nobel Prize in 1913. Karrer, after completing his doctoral dissertation on cobalt complexes in 1911 and earning his Ph.D., became Werner's lecture assistant. His attention soon turned to organic arsenical compounds, and Karrer's first paper on the subject, published in 1912, caught the eye of Paul Ehrlich, a renowned chemist in Germany whose work at the turn of the twentieth century had helped to explain the action of poisons and how to neutralize their effects by antitoxins. Ehrlich subsequently invited Karrer to join him as...