80 B Canadian Arctic Expedition, 1913-18 



flora of the island might have been enriched by another species. A still more 

 striking instance of a bird acting as a carrier of seeds was observed several years 

 ago by Mr. Bryan on Marcus Island, where he found no fewer than 40 seeds of 

 a tree of the madder family adhering to the feathers of a shearwater. These and 

 other similar facts show how the flora of oceanic islands may be transported by 

 birds from island to island or from continents to distant shores." 



Furthermore, that resident birds, as for instance the partridge, may well 

 transport many seeds from one place to another, has been pointed out by Dar- 

 win.^ 



With regard to other factors of dispersion, water for instance, we know, so 

 far, too little about the possibility of seeds retaining their vitality during pro- 

 longed immersion in salt water. The transport by means of ice may take place, 

 as pointed out by Simmons, when the question merely deals with narrow chan- 

 nels or fjords, but, nevertheless, more indirectly so, since the wind becomes a 

 more or less necessary, additional factor for carrying the seeds to the shore. 



However, even if we have reached no decisive conclusion as to the means 

 by which the migration was effected, nor by what roads it took place, we do 

 know that the plants exist there, that arctic and alpine species do occur in the 

 polar regions, and quite a number of these furthermore in the mountains farther 

 south. It seems even plausible to suppose that the mountains harbour a larger 

 number of arctic remnants than has really been accounted for, because the 

 arctic species in the mountains as well as the alpine species in the arctic region 

 may have submitted to a more or less pronounced modification in structure due 

 to the change of conditions. Such modification, in external structure especially, 

 may, as stated above, have resulted in the respective species appearing in dis- 

 guise, and being mistaken for separate species. In this way botanical manuals, 

 comprising floras of mountainous regions, are sometimes crowded with sup- 

 posed new species which actually are simply modified fosms or varieties produced 

 by change of environment, especially climate and soil. Consequently, when 

 dealing with plants scattered over large areas, we must consider whether they 

 represent analogous types or mere forms. Artemisia, Antennaria, Draba, and 

 several other genera have recently furnished an almost untold number of sup- 

 posed new species, regardless of the natural modification to be sought in "geo- 

 graphical distribution." 



Returning to the circumpolar species, these having been so admirably des- 

 cribed and their distribution discussed by some of the ablest botanists, the 

 danger of errors in their determination is but slight, even if more recently some 

 authors have ventured to make changes — as a rule wholly unwarranted. 



Having enumerated the circumpWar species, collected by the expedition, 

 we shall now offer a few data regarding their occurrence in other regions; more- 

 over, some points will be discussed relative to the southern, the alpine element, 

 which has also become distributed in the polar regions. 



In accordance with the enumeration of the circumpolar species, given in 

 the preceding pages, and the accompanying table, it will be seen that those 

 exhibiting the widest geographical distribution farther south are as follows: 



Cystopteris fragilis, Equisetum arvense, Lycopodium Selago, Trisetum spicatum, 

 Poa arctica, Festuca ovina, especially the variety brevifolia, F. rubra var. arenaria, 

 Eriophorum Scheuchzeri,E. vaginatum, E. angustifolium, Car ex incurva, the distri- 

 bution of which on this continent extends as far south as the Strait of Magellan, 

 C. rigida, which, however, in the Caucasus occurs only as the variety dacica, 

 SL plant, which Boissier (Fl. orient., Gendve, 1867-84) has enumerated as C. 

 rigida, but by Richter (PI. Europ., Leipzig, 1890-1903) has been referred to C. 

 caespitosa v. dacica. Furthermore Carex misandra, C. pulla, Juncus biglumis, 

 Salix reticulata, Polygonum viviparum, Oxyria digyna. Lychnis apetala, Cerastium 



' Darwin, C. On the Origin of Species. Fourth Ed. London, 1865, p. 432. 

 See also: Hesselman, H. Nagra iakttagelser Sfver vaxternas spridning. Botan. Notiser, 1897, p. 97. 



