The experimental results of Schein, Jesse and Wollan, Johnson and others seem to show that both the soft and the hard component of the cosmic radiation are secondary radiations produced by primary protons. This result involves, however, two difficulties, one regarding the propagation in interstellar space and one regarding the latitude and east-west effect of the soft component. The hypothesis is here put forward that the primary radiation consists ot negative protons as well as positive ones, the former being mainly annihilated at the top of the atmosphere thus giving rise to the soft component, the latter ones being transformed into mesons thus giving rise to the hard component. Arguments are given in favour of this hypothesis which is shown to be compatible with all the present experimental evidence, although not with the present quantum theory which gives a far too small cross-section for the annihilation of fast, negative protons. It follows, however, from arguments given by Heisenberg that abreak-down of the present theory must just be expected to take place for this process. and), S w a n n 14) and others have pointed out, a charged primary radiation can hardly be stable in interstellar space if it consists only of particles of the same sign. In this case it would, namely, due to the enormous distances give rise to electric and magnetic fields of considerable magnitudes, which would be incompatible with the further propagation of the radiation. From the east-west effect showing already an asymmetry at sea level it follows, however, unambiguously that the field-sensitive part of the primary energy spectrum, i.e. energies below 1.5 Γ 10 IΒ° e.v., contains more --177 --
Until recently it was generally assumed that the primary cosmic radiation consists mainly of positive and negative electrons.