126 BOTANICAL GAZETTE [auglst 



has been a continuous reaction of plant life upon environment; 



M 



the advancing zones leave soils behind them different from those 

 they found. Sphagnum swamps and peat bogs, into which the 

 lakes now under consideration are changing, are the last stages 

 in the life history of glacial lakes. 



The plant life of the small glacial lakes characteristic of 

 southern Michigan differs distinctly from most other hydro- 

 phytic societies. It is predominantly xerophil, while that of a 

 brook or river is predominantly hydrophil in character.^ It 

 differs from the flora of such lakes as have been studied by 

 MacMillan^ and Pieters '^ in not being influenced by waves, cur- 

 rents, spray, etc. 



II. GEOLOGICAL HISTORY. 



The lake selected for study is a *' kettle-hole " in the termi- 

 nal moraine which formed part of the northwestern shore of 

 ancient Lake Maumee, It is mainly fed by springs issuing from 

 the bottom and around the shores, though a small rivulet enter- 

 ing from the southeast contributes some surface water during 

 about half the year. The lake probably came into existence at 

 the close of the second advance of the ice sheet, and at that 

 time it was considerably larger than at present, due to the drain- 

 age from the melting ice. For some time following the forma- 

 tion of the lake it was apparently subject to sudden changes in 

 size and outline due to rapid fluctuations in the water supply. 

 There are two similar lakes within a mile to the eastward, with 

 which it formerly may have been continuous ; at present the 

 surface of the water is five inches lower than in either of the 

 other two lakes. 



The original lake must have been from sixty to eighty feet 

 deep in its deeper parts, and the surplus waters were discharged 

 through an outlet to the southwest which emptied into the 

 Huron river. The eastern shore was fifteen or twenty ro 

 farther east than at present; while from the southeast a wide 



^CowLES, IL C, Box, Gaz. 31 : 145, 190I. 

 3MacMili.an, C, Minnesota Botanical Studies, 50. 

 4PIETERS, A. J., U. S. Fish Com. Bull., pp. 57-79. 1901. 



ds 



