8 Bulletin Wisconsin Natural History Society [Vol. 12, Nos. 1 & 2 
few insects; the most common is a spider, which builds its web 
across the mouths of the pitchers of Sarracenias. The Droseras 
rarely hold an insect, and as one walks over the bogs there is no 
rising of insects about his feet, as in the case in fields at the same 
season” (he., p. 139). 
Cowles (1901) describes three types of ‘^undrained” swamps of 
which his first type is a characteristic bog of the extreme southern 
part of the bog area of North America. Zonal distribution and 
succession are clearly defined. ^^Algae and other hydrophytes 
characterize the lake and pond stages, and largely by their partial 
decay the water becomes shallow enough to support the vegeta- 
tion of a marginal swamp, particularly rushes and sedges. After 
these forms there appear the most remarkable plant societies of 
the entire series, characterized chiefly by Cassandra and other 
ericads with xerophytic structures. Following the shrub stage 
there is the tree stage in which the tamarack often dominates, 
though pines appear later and ultimately mesophytes. In these 
swamps one finds the most perfect example of the regular succes- 
sion of plant societies, and hence of zonal arrangement” (he., 
p. 181). 
Transeau (1903) has discussed the geographic distribution and 
ecological relations of the bog plant societies of North America. 
He shows (I.C., map, p. 406) an area extending from the upper 
Mackenzie basin to the Atlantic throughout which nearly all 
characteristic American bog plants appear in every bog; both 
to the north and to the south of this area the number of forms 
occuriing in each bog diminishes. He also discusses the glacial 
migrations of the bog plant societies, their distribution during 
maximum glaciation, and their postglacial northward migration. 
This paper was preliminary to a more extensive investigation 
(Transeau, 1905-1906) in which he studied the flora of several 
bogs in southern Michigan. The bogs studied lie in the Huron 
River valley; after describing the physiographic features and his- 
tory", the forestation, and the meteorology of the region, Transeau 
enters into a general consideration of the formation, development, 
and ecological conditions of the bogs; he discusses the various 
factors entering into the plant environment under three heads: 
physical, chemical, and biotic; he outlines the plant associations 
of seven bogs and shows the plant successions which take place 
