Report on recent developments in a non linear spinor theory of matter.

Heisenberg encloses a manuscript discussing certain properties of the propagation function of the non-linear wave equation. He asks for Pauli's opinion.

Pauli criticises the improper account of retarded four-potential in Landé's model for X-ray doublets sent to Sommerfeld.

Heisenberg writes on excitation times and line widths.

About Hans Thirring's work on gravity, a work by Rella, Hans Thirring's article 'Atombau und Krystallsymmetrie'.

Pauli sends an outline of a relativity article. He attempts to avoid any collision with Kottler's article. He makes proposals for uniform notation with Kottler.

Heisenberg writes about the quantum theory of the Zeeman effect. He makes a comparison with a paper by Bohr.

Heisenberg replies to Pauli's letter about quantum numbers. He also writes on Pauli's use of the summation principle for the calculation of Lande's g value and on the difficulties of the doublet-theory.