MIGRATION 39 



1. Spore-distributed, sporostrotes' ( Sporostrotae, a-iropd, 

 »|, spore, o-T(B(UTos, -ij, dv, strewn.) This includes all plants 

 possessing structures -which go by the name of spore, such 

 as the acinetes of Nostoc and Protococcus, the zoogonidia of 

 Vlothrix, Ectocarpus, etc. , the conidia, ascospores and basid- 

 iospores 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 {Spermatostrotae, 

 (TTripfw., TO, seed). This group comprises all flowering plants 

 in which the seed is the part modified or at least dissemin- 

 ated. The mobility of seeds is relatively small, except in 

 the case of minute, winged or comate seeds. 



3. Fruit-distributed, carpostrotes {Carpostrotae, Kaprrds, o, 

 fruit). 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 {Thallostrotae, flaAAds, 

 6, shoot). To this class are referred those plants, almost ex- 

 clusively 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 {Phytostrotae, (J>vt6v, t6, 

 plant). 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 dis- 

 tributed, as in tumbleweeds and in many grasses. 



Any investigation of migration to be exact must confine 

 itself to fixed forms, and for these the degree of perfection 



'Throughout the present paper, Greek or Latin equivalents have 

 been proposed for praetically all terms, because of the conviction that 

 a uniform international nomenclature is as imperative and as certain 

 for phytogeography, as it has been for taxonomy. The English form, 

 however, is given precedence, since it alone will suffice for the majority 

 of English-speaking botanists. 



