[Metamorphosis of Hyla arborea and of Rana esculenta in conditions of environmental pollution: a biostatistical study].

An extention to the largest possible numbers of animal species is a basic requirement when damages induced by pollutants are studies with a specific purpose of defining the concentrations of pollutants compatible with the conservation of the biochemical system. Animals should be bred in standard conditions, and the natural habitat is to be reproduced in the laboratory. The studies should also be planned favoring these statistical elaborations which are suitable of application also in case of interruption of the experimental design. The results of two experiments are reported in example, in which the metamorphoses of Rana esculenta and Hyla arborea are compared in standard conditions and during pollution with "fanghi rossi" (containing titanium dioxide).