Sphagnum bogs and transition bogs are described as to their plant associations, ecology of the species, ecology of the associations, and the succession of the associations. The influence of drainage, fires, and extraction of peat on both kinds of bogs is also discussed. The literature of Russian bogs is cited. The bogs investigated exceed 400 sq. km. Lists of plants for the various habitats are given, and diagrams show how the sphagnum bogs are encroaching on spruce and pine forests, the relation of dominance of certain plants to depth of water, frequency of occurrence of certain species in the 4 associations of the bogs, adaptability of certain species to various concentrations of mineral salts, and transformations of associations of the bogs both in nature and as a result of artificial interference.