Carl was invited to Graz to work with Otto Loewi to study the effect of the vagus nerve on the heart (Loewi would receive the Nobel Prize in Physiology or Medicine in 1936 for this work). While Carl was in Graz, Gerty remained in Vienna. A year later Carl was offered a position at the State Institute for the Study of Malignant Diseases (now the Roswell Park Cancer Institute) in Buffalo, New York and the Coris moved to Buffalo. In 1928, they became naturalized citizens of the United States.