Pauli fixes a convenient time for Kronig's visit to Zürich. He writes about a lecture he will give in Turin.

Pauli reports on the congress in Rochester. He writes about his discussion with Fermi about the neutrino experiments. He writes also on a talk about a new paper by Feynman.

Pauli makes comments on the second draft of Klein's article.

Heisenberg gives more calculations about zero-vectors and dipole ghosts.

Pauli replies to Heisenberg's letter of 30 January. He talks about the mirror-world, a problem vital for their theory, and about the connection with the nature of photons and Pi-mesons. He writes on the pre print: the Tam-Dancoff calculations should be published without Pauli's name.

Pauli talks about Bohr's paper on the statistical interpretation of quantum results which has its origin in the decision between observed object and measuring instrument. Critical remarks are made on the paper, but Pauli is still very positive about Bohr's conception, especially his view that the stationary states are as real as the particles themselves.

Pauli invites Ehrenfest to lecture on X-ray physics in a meeting in Zürich. He refers to the Ellis-Wooster heat experiment.

Pauli makes some theoretical remarks about the connection between self-energy difficulties and the existence of the electric charge.