[en] A research program to investigate several aspects of the hadronic interaction process at very high energies through nuclear emulsion techniques continues. An experiment at Fermilab searched for new particle production by neutrino interactions in nuclear emulsion targets inside the 15' bubble chamber. In this hybrid experiment, the deuterium-filled bubble chamber provided a rough location for the interaction vertex, and identified and momentum-analyzed the produced particles, while the emulsion provided a close look at the event vertex. A second exposure is planned for late 1980. Continued effort was directed to the study of multiparticle production processes in nuclei. In the earlier phases of this contract, protons and pions were used as the projectile; within the last few years, leptoproduction and nucleus-nucleus interactions have been investigated. There is, of course, considerable theoretical interest in this topic, since the development of intranuclear cascades, their multiplicities, and rapidity distributions are strongly dependent on the nature of the first interaction of the incident particle