360 : BOTANICAL GAZETTE [DECEMBER 
has gone into somewhat greater detail. In neither of these papers, 
however, is work reported on the typical peat bog plants. 
The main station for this study was Cedar Lake, at Lake Villa, 
. Lake County, Illinois. Supplementary work was carried on in 
bogs at Miller and Hillside, Indiana, and in a fen at Wolf Lake, 
Indiana. Cedar Lake is located about five miles south from the 
Wisconsin line and twenty-two miles west from Lake Michigan. 
It is situated in the Valparaiso morainic system (5) in a consider- 
able depression in the drift. The western border of the lake is deep 
and is covered by a floating mat of fibrous peat, while the north 
and east sides are shallow, and the vegetation passes from the usual 
hydrophytic forms in the water to shrubs, sedges, and grasses on 
the shores. This gives opportunity for comparing certain species 
as they grow in both peat and mineral soils, but with other condi- 
tions as nearly the same as is possible to find them in nature. The 
bog under consideration is of crescent form, fringing the west end 
of Cedar Lake, and is about 200 m. in width at its widest part. 
It is composed of a floating mat of peat that is only slightly decom- 
posed, except where it comes in contact with the clay basin at its 
landward margin. Here it has decayed, forming a hummocky 
black soil. Judging from its small size, the fact that it has made but 
a beginning in covering the lake although it is evidently making 
measurable progress, and the absence of all trees with the exception 
of a few young tamaracks, it seems evident that this bog is geo- 
logically very young. When compared with the vegetation of other 
bogs of the region, the plant life of this bog is obviously in the 
very early stages of plant successions, and it is inconceivable that 
it dates back to glacial times. Thus the supposition that all bogs 
are relicts from the glacial period seems less plausible. 
Field study 
In order to determine the exact form and physical relationships 
of the roots and rhizomes of bog plants, the preliminary work under- 
taken was the mapping of these parts in situ. The organs in 
question, some of which were very tender, were followed with the 
finger tips and then laid bare by the removal of all the material above 
them. Careful measurements were taken and the maps were made 
