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PROBLEMS OF LAKE BIOLOGY 



Fig. 9. A community of Eriocaulon, Potamogeton, Spargmiiitm, and Cast alia in a young bog lake. 

 Here the littoral vegetation, represented by Eriocaulon and Gratiola atirea, f. pusillus (submerged) has 

 been displaced from the subaerial soils by invading shrubs. They remain a member of the lake flora 

 because the water is still shallow near the sliore. Midge Lake, Vilas County, Wis. See also Fig. 8. 



Fig. 10. An old bog lake neariug closure. The only remaining aquatic vegetation is Nymphozanthus 



variegatus. Vilas County, Wis. 



