DISSEMINATION OF SEEDS. 137 



action of sea-water and of retaining vitality for a long 

 time, it is sensible to conclude that the seeds crossed the 

 ocean. 



Linnaeus in speaking of this method of dissemination 

 said, "Seeds embark upon the rivers which descend from 

 the highest mountains of Lapland and arrive at the mid- 

 dle of the plains and the coasts of the seas. The ocean, 

 too, throws, even upon the coasts of Norway, the nuts 

 of the mahogany and the fruit of the cocoanut tree which 

 have been borne on its waves from the far distant tropical 

 regions ; and this wonderful voyage is performed without 

 injury to the vital energy of the seeds." 



Experiments made by Darwin prove to us without 

 doubt that this method of distribution of plants is one 

 of the most important, though occasional, methods of 

 producing a change in the flora of a country. In "Origin 

 of Species," he describes several interesting experiments 

 from which he reached the conclusion that the seeds of 

 fourteen plants in every hundred "belonging to one coun- 

 try might be floated across nine hundred twenty-four 

 miles of sea to another country, and when stranded, if 

 blown by an inland gale to a favorable spot, would ger- 

 minate." 



DISSEMINATION BY GLACIAL ACTION. 



In studying the geographical distribution of plants, one 

 is struck with the identity of plants on mountain summits 

 separated from each other by hundreds of miles of low- 

 lands over which it seems impossible that these plants 

 could have migrated. Thus it has been found that many 

 species of plants living in the Alps and Pyrenees are 

 identical with those of northern Europe ; that the plants 

 of the White Mountains are like those of Labrador and 

 like those on the highest mountains of Europe. 



