Walter Sutton Theorizes that Chromosomes Carry the Hereditary Material

In "The Chromosomes in Heredity," Biological Bulletin 4 (1903) 231-51 American geneticist and physician Walter Stanborough Sutton advanced the theory that Mendel's factors were hereditary particles borne by the chromosomes, and that Mendel's laws for his factors were the direct result of the behavior of chromosomes in meiosis. 

Independently of Sutton, German biologist Theodor Boveri proposed a similar view in Ergebnisse über die Konstitution der chromatischen Substanz des Zelkerns (1904), causing the theory to be known as the "Sutton-Boveri theory or the Boveri-Sutton chromosome theory."

J. Norman (ed) Morton's Medical Bibliography 5th ed (1991) nos. 242.1, 242.2.