Glaser writes of his attempts to overcome the difficulty of "ghosts" in quantum electrodynamic field theory.

Källén writes to Pauli from CERN and gives the results of his calculations on the probabilities of dipole states.

Källén replies to Pauli about his difficulties as regards the S-matrix.

Källén writes of the result of his calculation of the splitting of a dipole state in the presence of an additional N-particle.

De Shalit asks questions regarding the contents of the preprint: 1) How is half-integer spin and integer iso-spin derived for the $\Lambda^{0}$ and $\Sigma$ particles 2) the role of the neutrino in weak interactions 3) He makes remarks on the non-linear equation of motion.

Glaser writes about the papers scheduled for the impending conference in CERN.

Källén writes from CERN on the discontinuous character of the S-matrix for the transition to the dipole ghost.