Some peculiar quantal and statistical effects in nuclear fission, which are not considered by most modern fission models, will be discussed. They are related to residual interactions and the localization of nucleonic wave functions in the nascent fragments. The peculiar properties of the di-nuclear system before scission are investigated with the methods of statistical mechanics. Theoretical arguments and experimental observations indicate that the nascent fragments form a system of interacting microscopic thermostates with very interesting and unexpected properties.
