Microbiology was born in 1674 when Antoni van Leeuwenhoek (1632-1723), a Dutch drapery merchant, peered at a drop of lake water through a carefully ground glass lens. Through this he beheld the first glimpse of the microbial world. Perhaps more than any other science, the development of microbiology depended on the invention and improvement of a tool, the microscope. Since bacteria cannot be seen individually with the unaided eye, their existence as individuals can only be known through microscopic observations. Indeed, it is interesting to speculate on how microbiology might have developed if the limits of resolution of the microscope were poorer.

The practical and scientific aspects of microbiology have been closely woven from the very beginning. Perhaps it is for this reason that microbiology as a field of study did not really develop until the twentieth century. Nineteenth century "microbiologists" were chemists and physicians...