Heisenberg gives a description of the present situation of the field-theory. In a more complete future theory there will exist no particles smaller than the universal length, and the divergences of the present theory will be avoided. He writes about more considerations about nuclear theory. The pair production observed up to now can only be interpreted as internal emission. About an experimental paper on shower production in great depth.

Heisenberg talks more about cosmic radiation at great depths and Heisenberg's conjecture that it consists of neutrinos. He continues his calculations with the new formulation of the quantum theory of waves. It leads to relativistic and convergent results, but energy and momentum integrals are not known because of the lack of a Hamiltonian.

Heisenberg writes about his marriage and gives more results about his attempt at convergent wave quantization: appearence of new infinities which cannot be avoid without loss of relativistic invariance. He talks about cosmic radiation: it seems as if his hypothesis of the neutrino origin of showers can be confirmed. He also talks about recent papers about the number of showers as function of layer-thickness.

Heisenberg talks about a letter by Blackett and his experiments about energy loss in Cu plates. He speaks of the possibility of the existence of heavy particles in the showers. He writes on Heisenberg's considerations about explosions in and the existence of a universal length.

Heisenberg objections about the impossibility of the localization of particles in the nucleus with a precision greater than h/($\mu$.c). He does not believe in a theory where $\mu$<M can be assumed. The theory of $\gamma$-ray interferences is a good example of the applicability of the explosion-hypothesis. He speaks of his belief in the existence of definite rest-masses of the same order of magnitude (h.c)/$\mu_{o}$.

Heisenberg talks about the political restrictions on contributors to the Sommerfeld issue of the "Annalen der Physick" and about his paper with Euler on cosmic radiation. The result refutes the theory of Uhlenbeck-Konopinski.

Heisenberg sends Pauli the manuscript of his paper on explosions and asks for his comments.

Heisenberg agrees with Pauli's interpretation of spin-inertia as "damping". He discusses the synopsis for the talk at the Solvay congress.

Heisenberg sends Pauli his part of the report for the Solvay congress, and adds technical details.

Heisenberg thanks Pauli for his part of the report and finds it a bit too difficult in certain parts. He agrees with Pauli's criticism of de Broglie's theory of photons. He was satisfied with his visit to the U.S.A.. He talks about some wrong results by Bethe in his attempt to explain the quadrupolmoment of the deuteron.