  There are investigated such cosmological models which instead of the usual
spatial homogeneity property only fulfil the condition that in a certain
synchronized system of reference all spacelike sections t = const. are
homogeneous manifolds. This allows time-dependent changes of the BIANCHI type.
Discussing differential geometrical theorems it is shown which of them are
permitted. Besides the trivial case of changing into type I there exist some
possible changes between other types. However, physical reasons like energy
inequalities partially exclude them.
