4 AQUATIC PHYCOMYCETES 



however, deal with any group (such as Synchytrium, Pliysoderma} and 

 so on) whose members are exclusively inhabitants of vascular plants. 



Phylogeny and Relationships 



The relationships and particularly the phylogeny of the fungi de- 

 csribed here have always had a peculiar fascination for the speculative 

 mycologist. Lengthy accounts have appeared almost since the beginning 

 of the investigations on aquatic Phycomycetes, each purporting to 

 show beyond question that these fungi are derived from algae by loss 

 of chlorophyll, or from higher fungi by the degenerative effects of 

 parasitism, or from simpler flagellate or monad ancestry (for a full 

 discussion in English of these theories see Atkinson, 1909b; Petersen, 

 1910; Cavers, 1915; Cook, 1928; Gaumann and Dodge, 1928; Fitz- 

 patrick, 1930). As might be expected of any discussions on the phylog- 

 eny of organisms so little known as these, all such accounts suffer 

 from the serious defect of being based on scanty and, too frequently, 

 inaccurate information. 2 No investigator of these fungi pursues his 

 studies for long before he comes to appreciate the enormous lacunae 

 in our present knowledge of them. It seems useless, therefore, to add 

 another chapter at this time to the already superabundant literature 

 on the subject. 



One paper on phylogeny should, however, be read carefully, in the 

 original, by those interested in the lower Phycomycetes — "Endophy- 

 tische Phycomyceten-Parasiten der Bacillariaceen und einige neue Mo- 

 nadinen. Ein Beitrag zur Phylogenie der Oomyceten (Schroter)" by A. 

 Scherffel (1925a). The conclusions of this distinguished Hungarian 

 investigator are of highest importance since they result from first-hand 

 study, over many years, of flagellates, algae, and aquatic Phycomycetes. 

 Very briefly, Scherffel considers that the aquatic Phycomycetes are 

 made up of two distinct series, the "Chytridineen" and the "Saproleg- 

 niinecn-Pcronosporineen." These he believes to have arisen from differ- 



1 A description of the genus Physoderma and brief mention of the family Physo- 

 dermataceae, with which it is coextensive, is given on pp. 482-483. For reasons 

 stated there, do treatment of the species is attempted at this time. 



8 See. for instance, Schussnig (1949), in which the Myrioblepharidinae, based 

 on Myrioblepharis (a mixture of a protozoan and pythiaceous fungus), is considered 

 a group under the Archimycetes (see p. 742). 



