INTRODUCTION 



Any truly comprehensive account of the interrelated and delicately 

 balanced society of plants and animals existing in waters should 

 consider all the entities, great and small, which form a part of it. As 

 is well known, green plants by their photosynthetic activities add new 

 materials in organic form to their environment and hence contribute 

 in a positive way to this society. Organisms lacking chlorophyll must, 

 for the most part, depend ultimately upon the synthesizers for their 

 existence. Yet such nonproducers are not to be regarded as mere im- 

 poverishers of the food supply, for they may perform useful and, in- 

 deed, necessary functions in the reduction, reworking, and transfor- 

 mation of organic materials, and, as Bigelow (1931) in referring to the 

 activities of marine bacteria has well put it, in the keeping in "action 

 of the cycle of matter through its organic and inorganic stages." By 

 far the greatest number of plants lacking chlorophyll belong in the 

 fungi, a group which, though primarily terrestrial, has a number of 

 aquatic representatives. The latter are for the most part Phycomycetes 

 ("algal fungi"), although the Myxomycetes, Ascomycetes, Basidio- 

 mycetes, and Fungi Imperfecti all contain water-living forms. Species 

 of Labyrinthula, for example, ordinarily regarded as Myxomycetes, 

 have been reported not only from fresh but from marine waters, where 

 certain ones undoubtedly cause destruction of eelgrass (Renn, 1936; 

 Young, 1943). Ascomycetes and numerous Fungi Imperfecti, hitherto 

 unknown, have been described in recent years from water (for example, 

 by Ingold, 1951, 1954, 1955). No doubt many others await discovery. 

 Of the Basidiomycetes, at least two genera of smuts, Doassansia and 

 Burrillia, have members which attack aquatic vascular plants (Fischer, 

 1953). 



The Phycomycetes are ordinarily considered the most primitive of 

 the true fungi. As a whole, they include a wide diversity of forms, some 

 showing definite relationships to the flagellates, others closely resem- 

 bling colorless algae, and still others being true molds. The vegetative 



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