272 measles. Some of the pathological changes revealed by many authors have been generalized as specific to measles and of these the appearance of Warthin-Finkeldey cells in lymphatic tissues has been recognized as the most characteristic change. However, a detailed picture of the pathogenesis of measles is still lacking. This is due firstly to the uncertainty of virological procedures for epideiniological virus and secondarily to the very restricted host range of measles other than the experimentalIy adapted strain. There are only a few reports on the pathological changes and clinical features of measles in monkeys (Blake and Trask, 1921a, 1921b; Cordon and Knighton, 1941; Shaft'er at a!., 1941; Taniguchi at a!., 1954; Sergiev at a1., 1960: Nil and Kamahora, 1963), and to date Sergiev 21 rr1.,(1960) have made the most extensive investigations of the virological and pathological features of the disease In recent years there has been great progress in research on the virology of measles (Blattner, 1957). Enders and Peebles (1954) first succeeded in isolating riteasles virus in tissue culture cells and showed its cytopathogenic changes fit Dino, I. e. syncytial formation as well as intranuclear and cytoplasmic inclusion bodies. These cytological changes caused IJy the agent ill Din'0\\, ere valuable in understand-ing the histological changes observed in aiuo.