  We present a method to decompose biochemical networks into subnetworks based
on the global geometry of the network. This method enables us to analyse the
full hierarchical organisation of biochemical networks and is applied to 43
organisms from the WIT database. Two types of biochemical networks are
considered: metabolic networks and whole-cellular networks (also including e.g.
information processes). Conceptual and quantitative ways of describing the
hierarchical ordering are discussed. The general picture of the metabolic
networks arising from our study is that of a few core-clusters centred around
the most highly connected substances enclosed by other substances in outer
shells, and a few other well-defined subnetworks.
