Who coined the the name "realist" for the 19th century artistic movement?

Gustave Courbet posted the words "Du Realisme" over his exhibition of paintings rejected from the 1855 Salon. The French writer Champfleury entitled his collection of essays "Le Realisme" in 1857. Courbet suggested that it was a critic who dubbed his paintings "realism" but the idea was probably "in the air".