Edmund Beecher Wilson emphasized careful experimentation and analysis in biology at a time when the field was rife with theories based on little more than speculation. Indeed, Wilson's work was instrumental in transforming biology into a rigorous, scientific discipline. Although known for his meticulous approach to the study of the structure and function of the cell, he never lost sight of biology as a unified field that included embryology, evolution, and genetics. His influence in biology was felt through his position as a professor first at Bryn Mawr College and then at Columbia University, and through his highly influential textbook, The Cell in Development and Inheritance. His study of chromosomes, and especially his discovery of the sex chromosomes, helped lay the foundation for the study of genetics and evolution in the early-twentieth century. Many of the problems that Wilson tackled, including the details of cell development, remain unsolved...