In this reply to a letter from Pauli, Bohr develops his exclusion principle and attempts to explain this rule in the framework of the electronic orbit model.

Pauli describes his latest work in quantum mechanic and compares it with Heisenberg's work. He discusses his results.

Pauli asks about stopping off at the Frankfurt institutes on his return trip from Göttingen.

Pauli expresses his doubts about the validity of his exclusion-principle in more complicated cases. He wants to discuss it in Tübingen on Jan. 9 1925.

Pauli anounces his arrival in Tübingen on 9 Jan. 1925.

Pauli talks about a formula made by Kramers and about his doubts about Goudsmith's idea on the spin of the electron.