Constants and Functions in Peirce's Existential Graphs

The system of Peirce's existential graphs is a diagrammatic version of first order logic. To be more precise: As Peirce wanted to develop a logic of relatives (i.e., relations), existential graphs correspond to first order logic with relations and identity, but without constants or functions. In contemporary elaborations of first order logic, constants and functions are usually employed. In this paper, it is described how the syntax, semantics and calculus for Peirce's existential graphs has to be extended in order to encompass constants and functions as well.