Microbe Hunters
Reprinted and translated many times.
Full text available online.
This book was the best-selling popular science book of its day and influenced many young readers to pursue science as a career. It began Paul de Kruif's career as a science writer (cover of his autobiography, right) for magazines such as Reader's Digest. 
Today's reviewers are less enthusiastic (my emphasis):
Paul de Kruif's book, Microbe Hunters, published in New York in 1926, was a romanticized medical “history,” written in a breathless style, that describes the lives and works of a dozen famous figures, ranging from Leeuwenhoek to Sir Ronald Ross. ... De Kruif's book, a best-seller in its day and influential among the young for a generation, now seems gauche and anachronistic.
Chernin, E. Paul de Kruif's Microbe Hunters and an Outraged Ronald Ross.
Rev Infect Dis 1988; 10 (3): 661-667.
doi: 10.1093/clinids/10.3.661
De Kruif’s stories are full-scale dramatizations, complete with fictional dialog of the historical subjects, and first person interjections of the voice of the narrator, De Kruif. The prose is breathless and exclamation points abound.
What can be said of Microbe Hunters as history? History is a selective business, and the historian is the one who chooses what to include, what to omit, and what to emphasize. The boundary between history and fiction is insecure, however. We assume, of course that the “facts” in history are “true”, that is, names, dates, events and so on are supported by evidence that attest to their existence. But what about dialog, such as enlivens Microbe Hunters so much? Clearly not all of De Kruif’s dialogs are direct quotes from archival sources, so how are we to read these passages? As fiction? As what might have happened? As what really did happen? Clearly, our understanding of the real events in these stories are shaped by how we interpret these invented dialogs. While apparently carefully researched, De Kruif’s embellishments and exaggerations render them frankly hagiographic and clearly reflect De Kruif’s heroic view of his field.
Summers, W. "Microbe Hunters revisited". International Microbiology (1998) 1:65-68.
