Jacques Loeb

Born in 1859 near Strasbourg, Jacques Loeb studied medicine in Germany and later built his career in the United States. He taught at several universities, including the University of California, before joining the Rockefeller Institute for Medical Research in New York, where he led work in general physiology.

Loeb became famous for experiments that aimed to explain life processes in physical and chemical terms. His best-known research showed that development in some animal eggs could be triggered artificially without fertilization, a result that drew wide attention at the time. He also studied tropisms—the ways organisms respond to light, chemicals, and other stimuli—and helped shape modern experimental biology.

He died in 1924, but his influence lasted well beyond his lifetime. By insisting that biological questions could be tested with carefully controlled experiments, he helped lay groundwork for later research in physiology, developmental biology, and biochemistry.