Heisenberg writes about two additions to his last letter, on a certain spinor and on the conditions for the finiteness of certain operators.

Pauli is looking forward to reading Jauch's forthcoming book on electrodynamics. He would prefer not to read the book in the proof-state, for this means a certain responsibility.

Pauli reports on his meeting with Delbrück. He discusses the empirical time scale of evolution and its agreement with theoretical prediction-following from "random mutations" and "selection". He talks about Delbrück's opinion as the most important unsolved problems in biology and the importance of the discovery of DNA.

Pauli writes about Jordan's article in the Bohrfestchrift which deals with the role of chance in biology. Pauli criticizes the use of the concept of chance in biology and evolution in particular.

Pauli makes remarks about a disscussion of the Lee model. He writes about the problem of evolution.

Pauli has returned from the USA and he plans to consider Janner's work.

Born gives some details on conclusions which were attacked by Pauli (probably in Florence).

W. Thirring made some comments on remarks which were made on his investigations (electrodynamics).