For a Lie algebroid, divergences chosen in a classical way lead to a uniquely
defined homology theory. They define also, in a natural way, modular classes of
certain Lie algebroid morphisms. This approach, applied for the anchor map,
recovers the concept of modular class due to S. Evans, J.-H. Lu, and A.
Weinstein.Comment: 11 pages, AmSLaTeX, 3 typos correcte