Heisenberg writes about his work on ferromagnetism. There are three approximations: 1)free electrons with Fermi-statistics, 2)Bloch's approximation of lattice potentials, 3)Heitler-London approximation of exchange of valency electrons of two atoms in the third approximation.

Heisenberg writes about Pauli's remarks on the H theorem in the case of the interaction of several oscillators and the connection with Dirac's theory.

Heisenberg writes about calculations about the theory of holes and on the self-energy of a particle. He replies to Pauli's question about the scattering of neutrons by protons and the difference between exchange forces and regular forces. He writes on the decay of the neutron and on his discussion with Bloch about the spin of the neutron being opposite to that of the proton.

Heisenberg writes about charge density and finiteness of self-energy.

Heisenberg gives detailed calculations to show that their simple method of incorporating the theory of holes into quantum electrodynamics leads to good results.

Heisenberg writes on the final results of the theory of holes. The whole scheme can be transposed into the quantum theory of waves. He talks about signs of a deeper connection between matter-field and radiation-field.

Heisenberg agrees with Pauli's calculations avoiding spin with Bose-statistics. The assumption that a single particle (electron) must be a trivial solution of quantum electrodynamics, should lead to spin with Fermi-statistics. The question is what kind of quantized wave theory will obey the following postulates: the number of particles corresponding to the waves is not necessarily constant, relativistic invariance, a single particle as trivial solution of the equations and energies are always positive.

Heisenberg makes some remarks on Pauli's and Weisskopf's theory. The infinite polarization of the vacuum is the result of certain parts of the quantum-theoretical formalism which need corrections.

Heisenberg cannot discover any mistake in his own calculations of the self-energy of photons.

Heisenberg asks questions in connection with Pauli's and Weisskopf's calculations, in particular how the self-energy of the electron becomes infinite. He writes about the results of calculations and about the scattering of light by light. He makes some remarks about nuclear physics (Fermi's and Bethe's calculations) and the moments of the proton and the neutron.