The letter contains detailed discussions of systems of hyper-complex numbers

Pauli gives his opinion on Bhabha's presentation in Zürich about meson and proton dispersion. He also reports about his correspondence with Heisenberg on the same subject.

Addition to the former letter.

Pauli gives a synopsis of his planned paper at the Solvay congress. He makes more comments on Heisenberg's damping-terms in the scattering of mesons by protons.

Pauli wants to continue his work with Kemmer on systems of hyper-complex numbers. He asks questions about application of quantum theory (perturbation) and on scattering of neutral mesons.

Pauli continues with his calculations with hyper-complex numbers. He adds some remarks on "neutretto"-scattering and the theory of mesons.

Pauli writes of the decision to postpone the congress because of the political situation.

A short addendum to the last letter.

Pauli discusses the vacant post of assistant. He writes about problems with Amaldi's scattering experiment, Villars' strong-coupling deuteron , symmetric weak coupling, Peng's (in: Proc. Roy. Soc. : 18 (1946), pp.119) attempt to remove divergencies, Heisenberg's S-matrix and Ma's redundant zeros.

Pauli comments on Gustafson's work.