Pauli refers to a paper by Weisskopf concerning the self-energy of the electron, which might be useful to Dirac on his discussion of the logarythmic infinities in the theory of holes. A copy of the paper is mailed to Dirac.

Pauli talks about de Broglie's report for the Solvay congress on the theory of the photon. Pauli does not believe in de Broglie's hypothesis that the rest mass of the photon is different from zero.

Pauli gives some calculations on an integral used by Born.

Pauli thanks Bhabha for his letter of the 26th March. He gives developments about meson and proton dispersion and comments on Bethe's latest work on meson theory and nuclear power and also his interpretation based on Fierz's study of Blau and Wambacher's results. Pauli sees a solution in new particles that have been observed in cosmic radiation. Heitlers theory seems to be unsatisfying. Pauli is working on a theory on high speed particles. He adds some remarks on the war and some physicists.

Pauli asks some questions concerning the relation of a paper by Majorana (published in: Nuovo Cimento: 1932) to Pauli and Fierz's theory about particles of arbitrary spin.

Pauli writes about his arrival at Princeton. He gives more details about his calculations regarding Majorana's equations.

Pauli writes from Princeton to Jauch in Zürich about Jauch's calculations on electron scattering. He asks questions about life in the Institute.

Pauli writes about his invitation to Ann Arbor. He is occupied with the divergence problem in the positron theory. He speaks of the damage war physics is causing to experimental physics. Weisskopf is invited to Princeton. (With some additional remarks for Mrs Weisskopf.)

The letter contains a short remark on self-energy and a longer one meson-theory, with reference to papers by Schwinger and Oppenheimer.