Egbert Anson Van Alstyne (March 4, 1878 - July 9, 1951) was a United States songwriter and pianist. Van Alstyne was the composer of a number of popular and ragtime tunes from the early 20th century. He was born in Marengo, Illinois. After some time touring in Vaudeville he moved to New York City, initially working as a Tin Pan Alley song-plugger until he was able to make his living as a songwriter. He teamed with lyricist Harry H. Williams. Wikipedia
Apparently, Conroy Casey was playing his own version of "Darkies' Spring Song," which both Jordan and Thompson heard, as they both deviated from Van Alstyne's score in the same manner. www.rag-time.com/fest/bio.htm
The definitive Wikipedia entry for Egbert van Alstyne. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Egbert_Van_Alstyne