The structure of the bismuth electronic spectrum suggested in Ref. 4 is discussed from the viewpoint of stability of the chosen initial state of a simple cubic lattice with respect to electron and phonon interaction. The types of various instabilities are considered, and the difficulties of the fulfilment of the Luttinger theorem on the number of carriers are discussed. The initial state is shown to be absolutely unstable with respect to the doubling of the period, the dielectric arising as a result. In order to obtain a semimetallic spectrum, an acoustic deformation is necessary; its existence, in principle, may be specified by the instability mentioned above due to nonlogarithmic terms. In this case the arising state has, apparently, a superstructure with the period ∼ 100 Å. A model of phase transitions under pressure is discussed.