Nilsson makes remarks on Rydberg's 1913 postulate of two new elements. He talks about the "wechselsatz' multiplet.

Nilsson reports on Siegbahn's response to Pauli's inquiries about Rydberg's new elements of 1913.

Nilsson reinterprets Rydberg's "triplets". He gives a modern level scheme.

Nilsson encloses a photo of J R Rydberg.

Källén writes on his recent attempts to simplify the calculations on quantum electrodynamics.

Källén encloses a manuscript dealing with the contents of his last letter of the 12 December 1949, in addition to a calculation on bosons in an external field.

Källén talks about calculation on an integral-representation of the S$_{c}$-function, avoiding the complex method of integration.

Hulthén comments on Jauch-Ning Hu's note published in: Physical Review: (May 1944), on nuclear quadrupole moment, on the implications of Amaldi's scattering results for theory of heavy-nuclei saturation, on his own publications and on the war situation in Holland.

Gustafson discusses a possible solution of the Dirac equation using "analytical combination" and the work of student S B Nilsson.

Gustafson sends a paper on mesons.