466 Canadian Record of Science. 



has been without doubt so arranged by nature that they 

 may be readily distributed at maturity by the wind. The 

 power of the wind as a distributor of the lighter class of 

 seeds has been underrated. The rapidity with which new 

 railroad tracks, extending into newly settled as well as old 

 settled country, have become tenanted, not by plants from 

 the neighborhood but by roving introduced plants, is a 

 striking evidence of the action of winds. Most of these in- 

 troduced plants, so common in cultivated fields, on road- 

 sides and on compost heaps, as well as on railroad tracks, 

 have seeds relatively light in weight, and provided in many 

 instances with appendages to facilitate their dissemination. 

 In districts where the forests have been burned over, the 

 native plants with which the burned area is soon peopled, 

 are generally of two classes — berry-bearing shrubs, the 

 seeds of which have been deposited by passing birds, and 

 plants like the Epilobium, birch trees and willows, whose 

 seeds have wings or awn attachments, which not only pre- 

 vent them from too quickly reaching the ground when they 

 fall at maturity, but also afford a better opportunity to the 

 wind to carry them to great distances. And these distances 

 are not to be measured necessarily by an acre lot or by 

 even the breadth of a township. Eecent investigation has 

 shown that volcanic dust, forced from a volcano during 

 eruption, may float through the atmosphere for many hun- 

 dreds of miles before descending. What may not be pos- 

 sible with light seeds when a gale of wind prevails ! I can 

 conceive it probable that the seeds of even arctic and sub- 

 arctic, as well as other plants, may have found themselves 

 occasionally by this means carried over great distances to 

 high peaks, mountain ranges and plains, to the southward, 

 where, on finding once more a favorable climate, soil and 

 physical surroundings, they would, each in its appropriate 

 place, germinate and develop. To the same cause would 

 probably be attributable the occurrence, on the White 

 Mountains, of plants like Geum radiatum and Paronychia 

 argyrocoma, which belong properly to the alpine flora of 

 the mountain ranges far to the southward. The great 

 range of so many sub-arctic and boreal lichens, also found 



