The phenomenon of conglutination was first reported by Ehrlich and Sachs (1902), and subsequently received attention from Bordet and Gay (1906) and Bordet and Streng (1909). However, a systematic study of the mechanisms involved did not appear until Coombs and associates, in a commendable series of papers, reviewed the earlier work (Hole and Coombs, 1947a), applied the test to certain virus sys...