Pauli replies to Lüders' letter of 26 April. He talks about problems of coordinate-mirroring, of particle-antiparticle conjugation and of invariance of the equation with regard to the continuous Lorentz group.

Pauli sends a manuscript of his article for the Bohrfestschrift to Lüders. He asks if some equations related to the interaction of charged bosons with protons and neutron spinors can be found already in earlier literature. He talks about commutability and anticommutability of independent fields with half-integer spin.

Pauli replies to Lüders' letters of 8 Dec and 13 Dec about elementary particle theory.

Pauli has just received J. Leite Lopes' paper "On the particle picture of quantized Bose Fields I", and mentions two relevant papers by Dirac, which Lopes did not quote.

Pauli plans a reconsideration of the Pauli-Fierz work (in: Z. Phys. : 106 (1937), pp.572) on the H-theorem.

Pauli makes an analysis of his own psychological state during recent years. He comment on a book by Buber which Kronig has sent him. He is impressed by Buber's subject-object philosophy and regards the concept as a fundamental one.

Pauli writes about Uhlenbeck's appointment in Utrecht. Pauli is glad that Kronig has written to him, in spite of Pauli's remark regarding the spin problem (in Tübingen). Pauli makes some remarks about him and Uhlenbeck. He thinks that Kronig should go to America, in spite of his doubts. He makes remarks on Jordan's and de Broglie's paper on the neutrino.

Pauli thanks Kronig for his letter about the two different sound waves in He II, which exists at different frequencies.