1903] BOG PLANT SOCIETIES 415 
were encompassed by broad-leaved forests. The oaks, hickories, 
maples, ash, and elm, following the lines of their specific habitat, 
the stream valleys or uplands, the sandy stretches left by glacial 
drainage, or the long lines of clay moraines, surrounded them in 
their northward progression. 
Probably if the pines, spruce, and: hemlock had ever been 
dominant in Ohio, Indiana, and southern Michigan we should find 
some evidences of their former occupation by way of isolated con- 
ifer areas. Excepting the southern and eastern shore of Lake 
Michigan and two small groups of pines in Ingham and Calhoun 
counties, Michigan, no conifer areas occur south of the Grand 
and Huron River valleys. When the early settlers moved into 
the region of southern Michigan, its forests were of the type 
commonly known as “‘oak openings.” Probably no type of broad- 
leaved forest would be more favorable for the preservation of 
conifer areas had they been dominant for any great length of 
time after the ice retreat. Where they have been planted within 
this region, they flourish and attain their normal proportions. 
Judging by the present distribution of Pinus Strobus and Pinus 
resinosa, the character of the soil in the vicinity of lakes Michi- 
gan, Huron, and Erie, and the meteorological conditions 
associated with these lakes, it seems probable that the conifers 
have reached their present distribution in the lower peninsula of 
Michigan by way of the lake shores. Probably the great bulk 
came by way of the southern end of Lake Michigan and from 
Ontario. 
In the west, the north, and the east, then, the xerophytic bog 
Societies are still found with their natural associates, the coni- 
fers (fig. 3). But in the Ohio valley they have been surrounded 
bya vegetation which bears no direct relation to them. Nat- 
urally, therefore, we should not expect to find an order of 
Succession between them. This seems to be the answer to the 
first question proposed. 
RELATION OF BOG SOCIETIES TO THE SWAMP SOCIETIES. 
This also gives us a new basis for answering the second ques- 
tion, as to the presence of the bog societies and swamp societies 
