“…In most instances fibrosarcomas have been relatively rare after whole-body irradiation of rats and mice (Upton, Kimball, Furth, Chrestenberry and Benedict 1960, Reincke, Stutz and Wegner 1964, Reincke, Stutz and Hunstein 1965 but rats which survived an LD70 exposure of 660 R had an incidence of 11 per cent (Koletsky and Gustafson 1955) . In the present series of whole-body irradiated rabbits the medium dose groups, which were irradiated at well below the LD50 level, had an incidence of 50 and 63 per cent and even the low dose of neutrons produced 27 per cent (table 4) .…”