In 1918, Sax took a job as an instructor in the Department of Genetics at the University of California, Berkeley, where he worked with E. B. Babcock on the genetics of the genus Crepis. In 1920 he took an appointment at the Riverbank Laboratories in Geneva, Illinois working on wheat genetics, but he moved on from that job soon after when he took a position at the Maine Agricultural Experiment Station in Orono, Maine.
