Before revision:  Our work extends previous results by Craciun and Feinberg for chemical reaction networks with stoichiometric space of maximal dimension. Specifically, a network iscalled injective if the species formation rate function is injective in the interior of the positive orthant within each stoichiometric class.
After revision:  We are concerned with the characterization of injective networks, that is, networks for which the species formation rate function is injective in the interior of the positive orthant within each stoichiometric class.