He developed the Moss System of blood groups in 1910 which was used to ensure safe blood transfusions before more detailed classifications based on refinements of Landsteiner's work came into practice.
After receiving a bachelor's degree in 1897 in civil engineering before he joined Johns Hopkins University to study medicine and graduated MD in 1905.
Landsteiner had identified three blood groups in 1901 and added a fourth in 1902 (AB).
[3] He later taught at Yale, Harvard and the Georgia School of Medicine where he served as dean.
Moss travelled around the world, taking part in expeditions such as the Crane Pacific Expedition[4] and studied immunization for diphtheria, tuberculosis and influenza.