  Following Hasse's example, various authors have been deriving divisibility
properties of minus class numbers of cyclotomic fields by carefully examining
the analytic class number formula. In this paper we will show how to generalize
these results to CM-fields by using class field theory. Although we will only
need some special cases, we have also decided to include a few results on
Hasse's unit index for CM-fields as well, because it seems that our proofs are
more direct than those given by Hasse.
