  Cosmic rays propagating in the Galaxy may excite a streaming instability when
their motion is super-alfvenic, thereby producing the conditions for their own
diffusion. In this paper we present the results of a self-consistent solution
of the transport equation where diffusion occurs because of the self-generated
turbulence together with a pre-existing turbulence injected, for instance, by
supernova explosions and cascading to smaller scales. All chemicals are
included in our calculations, so that we are able to show the secondary to
primary ratios in addition to the spectra of the individual elements. All
predictions appear to be in good agreement with observations. The fact that
data are explained with no need for artificial breaks in the injection spectrum
and/or in the diffusion coefficient as functions of momentum can be interpreted
as a strong indication that the phenomenon proposed here is in fact being
observed in Nature. We also show that there is very good agreement between the
calculated proton spectrum and the cosmic ray spectrum inferred from
observations of the gamma ray emission from clouds in the Gould's belt.
