[Development and variability of the properties of a type of nervous system during ontogenesis].

Age dynamics of development and variability of properties of the nervous system type was studied in the same animals (31 dogs) at the age from one month to ten years. Individual typological differences in the properties of the dogs' nervous processes were clearly manifested at the age of four to seven and a half months. Three phases were singled out in the development and variability of the properties: I--development phase; II--stabilization phase; III--extinction phase. In ontogenesis, the dogs displayed great differences in the degree of manifestation and the beginning of the phases. Relative stabilization of nervous system properties already set in by the beginning of puberty in dogs of the weak type (seven months of postnatal life) and at mature age in dogs of the strong type. Some elements of general behaviour of dogs of different nervous system types and the duration of the animals life, in relation to the nervous system type have been outlined.