10 Bulletin Wisconsin Natural History Society [Vol. 12, Nos. 1 & 2 
various stages of development and occupying many classes of de- 
pressions. Davis discusses the occurrence and distribution of 
peat bogs, and classifies the Michigan peat deposits preferably 
according to the land surface upon which they have been formed ; 
he makes two primary divisions in this classification: (A) peat 
formed over depressed surfaces, which he subdivides into five 
secondary classes, and (B) peat formed over surfaces not hollowed 
out, which he subdivides into seven secondary classes (l.c., p. 
115). Associations, succession, and zonation of surface flora are 
pointed out and the ecological factors controlling succession are 
discussed. A comparison of the process of filling of the lakes of 
the Northern and Southern Peniusulas of Michigan is made in 
which it is noted that zonation is more definitely marked and 
more developed in the southern lakes and that the species of plants 
below the water level are more numerous therein than in the cor- 
responding type in the Northern Peninsula (l.c., p. 269). 
The most recent extensive ecological study of bog flora is that 
of Dachnowski (1912) upon the peat bogs of Ohio. He gives 
rather fully the distribution of bogs in the various counties of 
the state, and describes in considerable detail the general bog 
flora, its associations, successions, and zonation. He distinguishes 
the following successions: (1) open water succession (plankton 
association); (2) marginal succession (submerged associations; 
semi-aquatic or amphibious associations; floating association); 
(3) shore succession {Decodon verticillatus association; Carex- 
Juncus-Scirpus association; Typha association; Calamagrostis 
canadensis association ; Phragmites communis association) ; (4) bog 
succession (bog meadow associations; bog heath associations; 
bog shrub associations; bog forest associations); (5) mesophytic 
forest succession {Accr-Fraxinus-Ulmus association), and under 
secondary successions those brought about by fire and by culti- 
vation. Dachnowski also discusses briefly the distribution of the 
Ohio vegetation during the last glacial period and the post- 
glacial migration of vegetation. 
The bog in which the present investigation is being conducted 
lies just east of Rhinelander, in Oneida County, Wisconsin, and 
has been named Ridgeway Bog since it lies immediately adjacent 
to a. picturesque wagon road known locally as “Ridgeway.’’ The 
