[en] The mean physical parameters were estimated for the planetary nebulae of two groups, regarded as a whole: planetaries of the common field and those belonging to a large group seen in the Galactic-centre direction. The mean central star temperature for the objetcs of each group was determined by solving the equation of the electron energy balance in the nebula. The optical depth and the collisional excitation of hydrogen atoms were taken into account. For the objects of both groups, the mean electron density, the mean electron temperature the mean degree of ionization, the dimensions and masses of the nebular envelope, and the principal parameters of central star were estimated. Some parameters were evaluated on the basis of the data, published in lists and catalogues. The results obtained, summarized in a Table, allow to place the objects studied into the general evolutional scheme of planetary nebulae. So, the members of the Galactic-centre group are in the earliest stage of the evolution, but the considered group of the common field occupies the intermediate region between optically thick and optically thin nebulae