Theodor Schwann

Theodor Schwann was born in Germany on 7 December 1810 and trained as a physician and physiologist. His landmark move came when he extended cell theory to animals, establishing that cellular structure wasn't unique to plants but fundamental to all life. Along the way he identified the cells in the peripheral nervous system that now bear his name, discovered and studied pepsin, demonstrated that yeast is organic rather than chemical, and coined the term "metabolism." He died on 11 January 1882, leaving biology with a framework it still uses to read the body.