“…Table I summarizes some of the reports of the electron microscopy of known leukaemogenic murine and avian viruses. Virus-like particles have also been reported in the lymph nodes (Dmochowski et al, 1959), bone-marrow (Braunsteiner et al, 1960;Murphy and Furtado, 1963), and blood (Almeida et al, 1963 ;Burger et al, 1964) of human leukaemic patients. Reports of viruses associated with leukaemia in man are summarized in Table II.…”