The incidence of thyric lymphosarcoma was greatly elevated by irradiation, in proportion to the dose (Chart 3). The thresheld fer thymic lyzphcua induction appears to be in the neighborhood of 500 r, The earliest cases were manifest in the fourth month, and the peak incidence cocurred from 7 te 12 months after exposure, contrary to epertence with most strains ofmise, thyntc lymphoeas were more coumon in meles than in females, In contrast to thymic lymphoid tusors, other forus of leukenia, itioluding lyzphonas, reticulum cell sarcomas, and rarely myeloid leukentas, eccurred relatively late in life. These were less numerous in the irradiated ice than in the controls, but this may be attributable te differences in longevity alone (Chart ). These will be Lllustrated and their relative frequency given. Twors of a variety of types have been encountered. Ovarian necplams were common «t all dese levels and very rere among controls (Chert S)»'as might be anticipated from earlier studies, sistologically thay include luteomas, granulosa cell tweors, tubular adenome of geruinal epitheliun, cystadenonas, henangiomas, and mixtures of these types. Their lower incidence at high dose levels is related to reduced longevity, as their latent period is relatively long (12-15 months). | DOR ARCHIVES - +