Pauli writes of his intention to publish with Weisskopf on the quantization of the relativistic scalar wave equation, and with Bose on statistics. He comments on Heisenberg's ideas about a future unified field theory.

Pauli is disappointed with Heisenberg's letter on nuclear physics. The indefiniteness of the go-functions in Heisenberg's and Majorana's nuclear theory is unsatisfactory.

Pauli replies to questions from Heisenberg in his letter of 4 November 1934. The self-energy of the electron in Pauli's theory becomes logarithmically infinite . This theory can only be developed with Bose-statistics. He writes about the Lagrange function of the scattering of light by light and about the magnetic moment of the neutron and the symmetry of the laws of nature with regard to the sign of the charge. He talks about the magnetic moment of the proton and the deuteron.

Pauli agrees with Heisenberg about V Neumann's paper. He also believes in the significance of a universal length.

Pauli agrees with Heisenberg's suggestion (letter of 2nd February) for the modification of his theory, and adds some remarks on this.

Pauli comments on a paper by Heisenberg about nuclear forces and its relation to the Yukawa-theory.

Pauli makes two remarks concerning Heisenberg's letter of 5 April about nuclear forces.

Pauli agrees with Heisenberg's letter of the 23 May which clarifies the question of decidability between various laws of force in proton-neutron scattering.

Pauli talks about the question of Beta-spectra. The literature gives ample evidence against Heisenberg's hypothesis.

Pauli is glad that Heisenberg's last letter of the 1st May has clarified the problem of frequency dependence of additional terms in Heisenberg's equation. He gives an outline of his paper for the Solvay congress.