  We calculate the probability distribution of the overlap between a spin glass
and a copy of itself in which the bonds are randomly perturbed in varying
degrees. The overlap distribution is shown to go to a delta distribution in the
thermodynamic limit for arbitrarily small perturbations (bond chaos) and we
obtain the scaling behaviour of the distribution with system size N in the high
and low temperature phases and exactly at the critical temperature. The results
are relevant for the free energy fluctuations in the Sherrington-Kirkpatrick
model.
