Introduction

The Hydractinia colonial organism has been studied for its allorecognition properties, which are thought to be a precursor for the MHC immuno-recognition seen in mammalian immune systems. We create a model of Hydractinia colonial growth which incorporates the three morphologies (stolon, fused mat and unfused mat) and the genes (which may occur in the following nine combinations on the two chromosomes: $ff\alpha \alpha$, $fr\alpha\alpha$, $rr\alpha\alpha$, $ff\alpha \beta$, $fr\alpha\beta$, $rr\alpha\beta$, $ff\beta \beta$, $fr\beta\beta$, $rr\beta \beta$,) thought to be primarily responsible for the allorecognition phenomenon.