Pauli writes on the concept of chance in biology and on the lack of a quantitative definition of biological probabilities. He suspects that the present conception of evolution is still essentially incomplete. The two parameters of selection and mutation are logically independent of each other. It is not the gene that is thesmallest unit of life but the cell as Bohr has emphasized.

Pauli replies to three questions of Jordan: 1) on heat conductivity, 2) on his possible visit to Hamburg, 3) on a problem which Delbrück might be able to answer.

Pauli congratulates Jordan on his appointment in Rostock. He makes short comments on Fermi's paper on quantum electrodynamics, on the paper by Fock and Weyl on the field equations of matter waves , which are invariant with respect to arbitrary rotations, and by which Einstein's Fernparallelismus comes to grief. He gossips about Einstein's lectures on Fernparallelismus and quantum theory. He writes about the gauge invariance and gives rumors about a new paper by Dirac.

Pauli thanks Jordan for sending him the booklet on "Komplementarität und Verdrägung". He writes of C G Jung's interest in these questions as well as in Rhine's experiments. He talks about Jung's "synchronistic" phenomena.

Pauli thanks Jordan for his book "Schwerkraft und Weltall". He has also read Ludwig's book on progress in projective theory of relativity. He thinks that the projective formulation (homogeneous coordinates) does not improve or add anything to Kaluza's formulation. He asks about the recent value of the Hubble constant. The idea of a changing gravitational constant seems plausible to him.

In connection with a planned lecture on cosmological problems of the theory of relativity Pauli asks for clarification on several points in Jordan's book.

Pauli makes several criticisms of Jordan's book.

Letter written giving Pauli's first impressions of Schrödinger's article "Quantisierung als Eigenwertproblem published in Annnalen der Physik. He develops the connection with the quantum mechanics of the Göttingen Physicists.

New research on Zürich nightlife.

Pauli asks for an offprint of Jordan's paper on complementarity in Rhine's experiments. He writes of his discussion with Jung about this subject.