Pauli describes his latest work in quantum mechanic and compares it with Heisenberg's work. He discusses his results.

Pauli makes some objections to Thomas' derivation of the missing factor in magnetic interaction of the spinning electron. He is opposed to its publication.

Pauli describes the theoretical tasks if the spinning electron is correct. He criticizes Thomas' relativistic derivation, published in: Nature : 117 (1926), 514.

Pauli has received from Rosental a copy of Bohr's article for "Dialectica" and Bohr's letter. This article will be of great help to him to clarify the contents of other articles in the issue, particularly Bohr's definition of "phenomenon". It would be a great help for the general editorial comment on the whole issue, if Bohr could return to Pauli the proofs of Einstein's article and also drop him a line on his opinion about the remarks which Pauli made himself in his letter to Einstein (of which Bohr has a copy). Every criticism is welcome.

Pauli sends Bohr a copy of his article for the Sommerfeld-Festschrift with a few comments. He writes about Kronig's work on band-spectra. He also talks about his good cooperation with Scherrer and about his plans for the vacation.

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.