436 BOTANICAL GAZETTE [DECEMBER 
Acidity tests show that the relative acidity is less than in the case of 
the cassandra-sphagnum and tamarack societies. The soil tempera- 
ture also runs somewhat higher as noted elsewhere. 
The First Sister Lake may be said to be dominated by three well- 
marked bog and two mixed societies in which bog and swamp species 
are brought into competition. The result can be 
foretold with considerable certainty. The bog vege- 
tation will sooner or later be replaced by the 
swamp species. 
BOG NORTH OF DELHI. — 
Two miles north of Delhi occurs an extensive 
bog which was formerly a mile and a quarter (2 *™) 
long by a half mile wide (0.8 *™) at its broadest part 
Fic. 7.—Delhi (fig. 7). The southwestern third has been cleared 
= rea alge and is in part under cultivation. The eastern and 
fcc @ Ard northern parts have been somewhat interfered with 
=r mile). by the cutting of timber, but areas occur which have 
been but little disturbed by these influences. Near 
the eastern margin are two small lakes, the last remnants of the larger 
lake which must have occupied this territory in early postglacial 
times. The basin is located in a clay moraine of the Erie ice-lobe, 
and probably owes its origin to unequal deposition by the glacier. 
The plant societies found about the southeastern lake will give an 
idea of the whole vegetation (fig. 8). 
Aquatic society.—The aquatic vegetation is represented almost 
wholly by the yellow water-lily, Nymphaea advena. This plant 
forms a broader zone completely encircling the lake and varying 
from 5 to 10 feet (1.5-3™) in width. Accompanying it occur Bra- 
senia purpurea, Ceratophyllum demersum, Lemna minor, and 
Spirodela polyrhiza. 
Typha-cassandra-sphagnum society.—On the floating margin of 
the bog substratum occurs a zone which partially encircles the lake. 
Near its outer edge Typha latifolia is the characteristic plant, but 7 
certain places it is wanting or extends the full width of the zone 
Chamaedaphne calyculata, Sphagnum cymbifolium, S. subsecundum, 
S. recurvum, Carex filiformis, Eriophorum polystachyon, and Salix 
