The internuclear cascade on the basis of the multiple theory of meson production is investigated in view of the so-called cosmic ray jet. The implication of Fermi’s and Heisenberg’s theories in this picture of the cascade is discussed purely on the kinematical ground. The predominant role in meson production of the successive collisions is played by the many-body collisions in the case of Fermi’s theory, while by the simple nucleon-nucleon collision in Heisenberg’s. The tunnel approximation of jets is shown to be applicable in these cases at sufficiently high energies. The criterion of this approximation is given by calculating the number of mesons which get off the tunnel. The possibility of accompanying grey tracks besides evaporation particles arises from these low energy mesons. The anisotropy in the angular distribution of jet particles, is shown to be stronger in Fermi’s model than in Heisenberg’s model. The present experimental evidences are too meager to choose one of these theories, but seem preferable to Fermi’s theory rather than to Heisenberg’s.