Why there is no formal ontology in Bolzano

Bolzano is often mentioned today as having laid the foundations for a "form al ontology." He is supposed to have a theory of the "something in general" that is an ontological one. In fact his combinatory theory of representati ons in themselves allows an accounting for constituting "somethings" of dif ferent degrees, in a recursive way. However, you must doubt whether Bolzano 's strict realism, even concerning the representations in themselves, makes room for what could really be called "formal objects."