Heisenberg thanks Pauli for his preprint on the conservation of leptonic charge. He sends by the same mail a first blueprint of the Lee model paper. He writes about further progress in his calculations.

Pauli reports on Jost's results concerning the TCP-theorem.

Pauli's letter discusses some recent Beta-decay experiments in the U.S.A. and their bearing on the parity problem. The two component theory is not tenable in the light of these field theories, a deeper understanding of the parity problem is not possible.

Pauli refers to a paper by Heisenberg and explains a passage which was misinterpreted by Källén.

Pauli replies to Lüders' comments on Pauli's last paper.

Pauli writes about a problem which has still to be solved: the application of the theory of invariants to the decay of My-mesons. He writes of his discussions with Heisenberg on a special case of the Lee-model.