This letter contains another mathematical question in connection with an equation in de Broglies's theory which Pauli wants to criticize in his report to the Solvay-congress.

Pauli writes about the mathematics of hyper-complex numbers and the application for the case of higher spin.

This letter contains more calculations with hyper-complex numbers and applications to systems of particles with given spin.

About the postponement of the Zurich congress.

Pauli asks personal questions in connection with the war. He makes remarks on Heisenberg's fear of continuing his correspondence with Pauli for political reasonsnd writes about the mathematical treatment of particles with higher spin.

Pauli asks a question about a possible visit to Edinburgh. He makes some remarks on various papers which appeared recently.

The letter contains more remarks on the same model.

Pauli aknowledges receipt of Kemmer's manuscript. He asks him to look into the latest American papers on nuclear forces.

Pauli makes some remarks on the present state of the meson-theory. He writes about measurements of energy density, charge density and particle density. Ha also makes some personal reports on common colleagues.

The letter asks further question about the same model discussed in his letter of 14 Nov, concerning impact cross-section of suchparticles.