  We express the contribution of certain maximal parabolic Eisenstein series to
the spectral side of the Arthur--Selberg trace formula for GL$(n)$ in terms of
zeroes of Rankin--Selberg $L$-functions, generalizing previous results for
GL(2) and Hecke $L$-functions. As applications, we prove a lower bound for the
sum of these zeroes, and a base change relation between the zeroes in the case
$n=2$ for cyclic extensions of prime degree.
