Physiology and Phylogeny in the Water Molds-A Reevaluation

Abstract

Current knowledge of the essential features of the synthetic capacities of the aquatic Phycomycetes is summarized in a figure. The writer''s concept of relationship among the major groups is essentially the same as it was in 1950, however more detailed data about the uniflagellate series have now made it possible to relate the Blastocladiales to the Chytri-diales by means of a simplified, single, broad line of evolution of synthetic capacities. From these data the conclusion is drawn that, (a) in uniflagellate series the synthetic capacity of the Blastocladiales is at a more highly evolved level than that of the Chytridiales; and (b) in the biflagellate series, the nutritional characteristics of the Leptomitales and aquatic Peronosporales tend to relate these two orders more closely to one another than to the Saprolegniales.