Some aspects of the biology of Pilaira species

Abstract

This thesis describes investigations into Pilaira anomla, P.caucasica and P.moreaui, also a brief review of previous work on these coprophilous mucoraceous fungi. The isolation of Pilaira from dung is described, together with measurements of the diagnostic characteristics of a number of isolates. P.anmala was found to produce a vegetative 'growth ring' when the mycelium was briefly exposed to light. This phenomenon was associated with a marked temporary reduction in vegetative growth, P.caucasica and P.moreaui did not show any such conspicuous responses. The carotene pigments present in P.anomala have been analysed in detail and related to analyses in other members of the Mucorales. The morphology and location on the mycelium of the priraordia of the sporangiophores has been studied. Sporangiophores were initiated by all three species in darkness, but a requirement for light by P.anomala for the development of the sporangium was found. The external morphology of the Stages of sporangiophore development are described, together with a brief study of the development of the columella and spores within the sporangium in all three species. The durations of the Stages of development have also been measured. The pattern of growth of the developing and mature sporangiophores has been studied. The twisting of the mature sporangiophore during growth was measured in P.caucasica and demonstrated in the other two species. The production of 'stolons' - abnormal sporangiophores, has been described. A detailed analysis of the positive phototropism of the young and mature Stages of sporangiophore development has been made, including the reversal of tropism under liquid paraffin and a close examination of the location of the bending zone in all three species. Finally, indication has been made of topics suitable for further investigation.