  We present magnetoresistance (MR) measurements performed on quench condensed
granular Ni thin films which are on the verge of electric continuity. In these
systems the electric conductivity is believed to be governed by the resistance
between a very small number of grains. The films exihibit sharp resistance
jumps as a function of magnetic field. We interpret these findings as being the
result of magneto-mechanical distortions that occour in single grains which act
as bottlenecks in the dilute percolation network. The observed features provide
a unique measure of magnetostriction effects in nano-grain structures as well
as being able to shed light on some of the properties of regular granular
magnetic films.
