A New Heterophile Antigen Common to Avian Erythrocytes and Some Varieties of Genus Pasteurella; Its Significance in the Classification of Birds

The presence of a new heterophile antigen, in some strains of the haemorrhagic septicaemia group of bacteria and in the erythrocytes of birds, is described. In contrast to the apparent chance appearance of this antigen in members of the Pasteurella group of organisms, it is present in many birds in an orderly fashion. The significance of this heterophile antigen in bird erythrocytes is discussed from the standpoint of species evolution. Additional strains of the haemorrhagic septicaemia organism containing Forssman's heterophile antigen are described.