The second session was dedicated to the exposition of the available basic knowledge concerning measles virus. The broad outlines and much specific information were provided by Dr. Enders who began by recalling some of the early landmarks in our understanding of the nature of the etiologic agent. These include, in particular: Hektoen's demonstration in 1905 of the presence of the agent in bacteria-free acute-phase blood; Anderson and Goldberger's reproduction in 1911 of disease in monkeys, including at least one passage with filtered serum; the work of Blake and Trask, who in 1921 reported repeated passage of infection in monkeys by way of filtered nasopharyngeal washings, and the tantalizing but inconclusive efforts of Plotz, Rake, and others to cultivate the agent in chick embryo tissue systems in the period 1938-1939.
The modern era began in 1954 when Enders and Peebles reported the evolution of cytopathic changes in monolayer cultures in primary