  We give geometric and algorithmic criterions in order to have of a proper
Galois closure for a codimension one germ of quasi-homogeneous foliation. We
recall this notion recently introduced by B. Malgrange, and describe the Galois
envelope of a group of germs of analytic diffeomorphisms. The geometric
criterions are obtained from transverse analytic invariants, whereas the
algorithmic ones make use of formal normal forms.
