1. Spore-distributed, sporostrotes. This includes all plants possessing structures which go by the name of spore, such as the acinetes of Nostoc and _Protococcus_, the zoogonidia of _Ulothrix_, _Ectocarpus_, etc., the conidia, ascospores, and basidiospores of fungi, the tetraspores of red seaweeds, and the gemmae and spores proper of liverworts, mosses, and ferns. These are almost always without especial contrivances for dissemination, but their extreme minuteness results in great mobility. 2. Seed-distributed, spermatostrotes. This group comprises all flowering plants in which the seed is the part modified or at least disseminated. The mobility of seeds is relatively small, except in the case of minute, winged or comate seeds. 3. Fruit-distributed, carpostrotes. The modifications of the fruit for distribution exceed in number and variety all other modifications of this sort. All achenes, perigynia, utricles, etc., properly belong here. 4. Offshoot-distributed, thallostrotes. To this class are referred those plants, almost exclusively cormophytes, which produce lateral, branch-like propagules, such as root-sprouts, rhizomes, runners, stolons, rosettes, etc. Migration with such plants is extremely slow, but correspondingly effective, since it is almost invariably followed by ecesis. 5. Plant-distributed, phytostrotes. This group includes all plancton and surface forms, whether motile or non-motile, and those terrestrial plants in which the whole plant, or at least the aerial part, is distributed, as in tumbleweeds and in many grasses.