The discovery of the germ led to safe surgery, large-scale vaccination programs, dramatic improvements in hygiene and sanitation, and the pasteurization of dairy products. Above all, it set the stage for the emergence of antibiotic medicine. This book deals with the ideas and experiments of the giants of microbiology, Pasteur and Koch, as well as less-well known figures such as Casimir-Joseph Davaine and Max von Pettenkofer.