The interactions of antinucleons in complex nuclei of emulsion have been studied. The three main lines of investigation are the following: 1) The annihilation at rest of antiprotons in the complex nuclei of emulsion has been studied and a method has been devised of separating the annihilations in the light and the heavy elements. By identifying the annihilations on the neutrons and protons in light elements it is shown that the ratio of the probabilities of annihilation proceeds equally through the singlet and triplet isospin channels. The apparent departures from this result for heavy elements have been accounted for by the secondary interactions of the annihilation products in the parent nuclei. 2) The antiproton is used as a nuclear probe to determine the distribution of memento of the nucleons of light elements such as carbon. It is found that the momenta of the nucleons of light elements such as carbon. It is found that the momenta follow the distribution expected from a harmonic oscillator model of the nucleus as found by other techniques and that these momenta extend up to about 400 MeV/c. 3) The interactions of antineutrons produced by the charge exchange of antiprotons with the emulsion nuclei have been studied and it has been shown that the general characteristics of the antineutron stars such as the sizes, the mean multiplicities of secondary mesons and their energy spectra are similar to those of antiproton stars. Finally, the charge exchange cross-section for antiprotons of moan energy 125 MeV has been determined and is found to be (17 ± 6) mb. This is close to the value expected from the calculations made for the charge exchange cross-section of antiprotons in complex nuclei
