Jelly Roll Morton probably wrote Frog-i-More rag in 1908 to accompany a fellow vaudevillian known as Frog-i-More, a contortionist who performed in a frog costume, but he did not deposit the music for copyright until 1918 for fear that any form of public record was an invitation to purloin his ideas.
Morton’s piano style and musical greatness are nowhere better demonstrated. All of the most typical features are abundantly evident: his wealth of melodic invention and skill in variation; the tremendous swing; his feeling for formal design and attention to detail; his effective use of pianistic resources; the contrasts of subtle elegance with hard hitting drive; and the variety of harmony yet freedom from complication and superficial display.
This according to “Jelly Roll Morton and the Frog-i-More rag” by William Russell, an essay included in The art of jazz: Essays on the nature and development of jazz (New York: Oxford University Press, 1959, pp. 35–36).
Today is Morton’s 135th birthday! Below, a performance of the piece via mediated piano roll.