  The showers of cosmic rays entering the Earth's atmosphere are main sources
of information on cosmic rays and are also believed to provide information on
elementary interactions at energies not accessible to accelerators. In this
context we would like first to remind the role of inelasticity K and elementary
cross section $\sigma$ and then argue that similar in importance are
fluctuations of different observables. The later will be illustrated by
multiplicity fluctuations in hadronic and nuclear collisions.
