Statistics for A high frequency change, which is both inducible and reversible, results in altered colony morphology of a fungal symbiont (Neotyphodium lolii) and dwarfing of its grass host (Lolium perenne) : this thesis is presented in partial fulfilment of the requirements for the degree of Master of Science (MSc) in Microbiology at Massey University, Palmerston North, New Zealand