Bohr has heard that Pauli developed new thoughts on the mystic of relativity in the atom theory and is asking for some developments.

Bohr discusses Goudsmit and Uhlenbeck's work published in: Nature : 117 (1926), pp.264. Thomas has explained the missing factor of 2 by calculating the relativistic motion in: Nature : 117 (1926), pp.514. Thomas' note is enclosed.

Bohr comments on a book by A Pauly (1905) on "Darwinism and Lamarchism". Bohr gives his attitude to the great progress in biology and psychology made in recent time, in the light of the results of atomic physics as regards the description of phenomene.

Baade gives reply to some questions asked by Pauli: 1) About the deviation of light in the gravitational field. 2) About the gravitational red shift. 3) About the Hubble constant.