Neonatal ducks and chickens are exposed to a wholebody X-irradiation ranging from 100R to 3, 000R at a dose-rate of 185R per min. Lethal doses to 50% in 30 days are estimated to be 500R for the ducks, while 800R for the chickens. The ducks appear to be much more radiosensitive than the chickens. Histopathological observations of various organs of the exposed specimens after death reveal remarkable alterations: Particularly lymphoid organs are affected much more in the ducks than in the chickens at lesser doses than 1, 000R.
Morphological characters and breeding habits of Rana ishikawae are observed in some detail in Okinawahonto and Amamioshima. During the breeding season, a male frog has stayed in a hole along waters. He invites different females by calling to the same hole, and spawnings are made by these females at different times. The breeding season seems to be taken place in the winter season in Okinawahonto, while from spring to early summer in Amamioshima. Well-developed and young larvae are observed in summer in Okinawahonto, while in winter in Amamioshima. Well-developed larvae are obtained in streams of both islands through the year. A considerable morphological difference is present on the back spot and tubercles between the frogs from Okinawahonto and Amamioshima.
Immunoprotection against EAT challenge is achieved by preimmunization of mice with rat/EAT hybrid cells with a nearly complete retention of EAT genome and partial segregations of rat chromosomes. The acquired immunity is highly specific for the parental EAT: The mice immunized with some other hybrid cells unrelated to EAT have died of tumor without protection against EAT.