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AN attempt to explain neutron-proton interaction made by Yukawa1 in 1935 has been brought to general notice2,3 in connexion with the new experimental evidence for the existence of a 'heavy electron'4,5,6.
WE have generalized a theory put forward by Yukawa1 showing that nuclear forces can be explained by assuming the existence of new particles of mass about two hundred times that of the electron. Our theory is relativistically invariant, and in its present form gives results which we believe are of actual significance for cosmic ray and nuclear phenomena.