<p> The investigation was carried out in order to determine the nature of some aberrant asci obtained, at a high frequency, from a single cross in Neurospora crassa. The subsequent investigations shed light on an aspect of pyridoxine metabolism and the nature of its genetic control, as well as showing the existence of dicentric chromosome and its great instability when present in the disomic condition. </p> / Thesis / Master of Science (MSc)