Pauli writes on some afterthoughts about Heisenberg's letter.

Pauli writes that his view that Delta-type interaction between more than two neutrinos must lead to infinities was influenced by a paper by Thomas (Phys. Rev. 47,903). This does not affect Pauli's and Heisenberg's case.

Pauli takes back what he said in the last postcard and confirms Heisenberg's calculations.

Pauli comments on a paper by Uhlenck-Konopinski and by Anderson-Neddermeyer on particles with masses between that of electron and proton, which opens completely new vistas.

Pauli congratulates Heisenberg on the birth of his child. He makes a remark on the cut-off frequency of long waves and about Yukawa's theory of nuclear forces.

Pauli talks more about cosmic rays and the occurence of light particles (electrons) in showers.

Pauli reacts sharply on "non-scientific secondary conditions" of certain publishers as regards the racial origin of scientific authors. He talks further about cosmic ray experiments and their interpretation.

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

Pauli has read with great interest Heisenberg's paper on the S-matrix, but as no method is given how to determine it, the work remains purely programatic.