A self-taught scientist determined to bring science out of the laboratory and into the practical arena, French-Canadian Felix d'Herelle (1873-1949) made history in two different fields of biology. Not only was he first to demonstrate the use and application of bacteria for biological control of insect pests, he also became a seminal figure in the history of molecular biology. This book is the first full biography of d'Herelle, a complex figure who emulated Louis Pasteur and influenced the course of twentieth-century biology, yet remained a controversial outsider to the scientific community.