ROWLEE: RELATION OF MARL PONDS AND PEAT BOGS 411 
decidedly hard, that is, it is impregnated with lime while the water of 
peat bogs is soft, that is, it is not alkaline in its reaction. 
In a series of careful studies Davis has shown that marl is com- 
posed mainly of the remains of the alga Chara. Chava thrives in 
hard water and its cell walls are impregnated with calcium carbonate. 
In many marl ponds a complete transition from the living Chara to 
characteristic marl can be seen. Since Chara grows submerged and 
the principal bog plants grow emerged it is evident why there is filling 
at the shore in the one and in all parts of the pond in the other. 
In sounding many peat bogs in western New York, the writer was 
somewhat surprised to find many of them underlayed with marl. 
Fic. 1. Marl bog, northeast side of Lowry’s Pond, West Junius, Seneca Co., 
N. Y. Species of sedges the dominant vegetation form. 
The assumption had been that the alkaline or nonalkaline character 
of the water originally filling the depressions determined whether bog 
vegetation or marl pond vegetation would develop in it. Is it possible 
that a pond might be alkaline during one stage of its existence and 
then become non-alkaline in a later stage? An affirmative conclusion 
seems inevitable. 
It is Dachnowski’s view that there are changes in the vertical or 
historical succession in the bogs, for he says: “While working on the 
ecology of ravines near Ann Arbor, Michigan, I became convinced 
that the reactions of plants on their habitat were equally as great and 
profound, in some cases, as the influence of edaphic and climatic 
