Ivan Petrovich Pavlov was born. A Nobel prize winning physiologist and scientist, Pavlov's groundbreaking work on conditioned reflexes derived from his observations of the reflex regulation of the activity of the digestive glands in dogs had a profound impact on modern behavioral psychology; influencing the work of such luminaries as John B. Watson, Edward Thorndike and B.F. Skinner.

(Note: Sources drawing on the old style (O.S.) Julian calendar record Pavlov's date of birth as September 14th 1849)