Cameron : Morphology of Blue-Green Algae 419 



occur. Distinctions have also been made between plants which differ morpho- 

 logically in some details but are actually only growth forms of the same species 

 found in a slightly different environment. Microcoleus, for example, has been 

 considered as a multitrichomatous organism occurring only on soils, and blue- 

 green algae are said to be more abundant in cultivated than in noncultivated 

 areas (Tiffany, 1951). Such restrictions have not been found valid upon fur- 

 ther study. An exhaustive review of specimens and their subsequent enumera- 

 tion on the basis of pertinent characteristics, as for the coccoid Myxophyceae 

 (Drouet and Daily, 1956) is needed for the other blue-green algae. Culture 

 studies, although valuable, are often confusing in that the cultured plant can 

 lose its identity with more famiUar forms occurring in the natural environ- 

 ment. Changes in any one of the environmental conditions can result in 

 plants differing from the original organism in form and structure, as well as 

 regeneration rate, cell division, size, shape, and contents. Pleomorphism 

 among the blue-green algae will remain as a confusing factor until an extensive 

 review has been made of all available material in herbaria and in other collec- 

 tions, and investigations performed on the growth of organisms in both natu- 

 ral and induced environments. 



A cknowledgment 



Appreciation is expressed to Francis Drouet, who has made suggestions, 

 loaned herbarium specimens and reference materials, and given generously of 

 his time and assistance. 



Rejerences 



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