Ferdinand Seidl 1859 1940 and Julia Mayer 1858 1932 of Bavaria Germany

This is my maternal great grandfather. He was born 17 Dec 1859 i Bavaria, Germany; At 38 years of age he traveled to the U.S. on a ship departing Hamburg called "Pretoria. The date of his departure date was 12 Jan 1902. In 1889 he married Julia Mayer (1858-1932)(also of Germany) and they took up residence in Woodford County,Illinois. He was a prominent doctor in the city of Benson, Ill.

I am trying to find relatives of his family in Germany.