  Photographic F band photometry of a sample of 36 Abell clusters has been used
to study the relation between the magnitude $M_1$ of the brightest cluster
member and the Schechter function parameter $M^*$. Clusters appear segregated
in the $M_1$-$M^*$ plane according to their Rood \& Sastry class. We prove on a
statistical basis that on average, going from early to late RS classes, $M_1$
becomes brighter while $M^*$ becomes fainter. The result agrees with the
predictions of galactic cannibalism models, never confirmed by previous
analyses.
