The Body: A Guide for Occupants

by Bill Bryson

The story of Fleming’s accidental discovery of penicillin has been told many times, but hardly any two versions are quite the same. The first thorough account of the discovery was not published until 1944, a decade and a half after the events it describes, by which time details were already blurring, but as best as can be said, the story seems to be this: In 1928, while Alexander Fleming was away on a holiday from his job as a medical researcher at St. Mary’s Hospital in London, some spores of mold from the genus Penicillium drifted into his lab and landed on a petri dish that he had left unattended. Thanks to a sequence of chance events—that Fleming hadn’t cleaned up his petri dishes before departing on holiday, that the weather was unusually cool that summer (and thus good for spores), that Fleming remained away long enough for the slow-growing mold to act—he returned to find that the bacterial growth in the petri dish had been conspicuously inhibited.