deaths
December 20, 1921
Julius Richard Petri, German microbiologist (born 1852)

Julius Richard Petri
Julius Richard Petri was a German microbiologist who is generally credited with inventing the device known as the Petri dish, which is named after him, while working as assistant to bacteriologist Robert Koch.
December 20
December 20 is the 354th day of the year in the Gregorian calendar; 11 days remain until the end of the year.