Studies in the water moulds of the Royal Holloway college grounds

Abstract

The grounds of Royal Holloway college afford habitats for a wide variety of aquatic fungi. Those studies have been carried out in two selected families of water moulds, Saprolegniaoeae and Pythiaceae. A vast body of literature on the Saprolegniaceae has accumulated, chiefly in the United States, but comparatively little work on the family has been done in Britain, owing, probably, to the extraordinary difficulties of identification of the members of this group of fungi, a review of the small amount of literature on British Saprolegniaceae emphasises the need for the detailed observation of each species throughout the year. Comparison of a number of species collected, with the corresponding species described by Coker in his monograph on Saprolegniaceae (1923) and with the previous British records, reveals that while some species agree closely with these descriptions, and remain constant throughout a period of culture up to two years in length, other species show differences and a tendency to vary during culture. An illustrated account is given of Pythium undulatum, and the literature on it is discussed. Apparent departures of this species from the usual conception of members of the genus Pythium necessitate a proper appreciation of the characteristics of the genus as a whole. An account is, therefore, given of the features of the mycelium and sexual reproduction of those species of Pythium which have previously been described in detail, and the classification of the genus is discussed, in order to find justification for the taxonomic position of Pythium undulatum in the family Pythiaceae.