MODES OF DISPERSION. 87 



from its banks when it suddenly overflows them. Thus many 

 Alpine plants have found their way as far as Strasburg, and the 

 Erinus of the high mountains has been transplanted by the 

 Eh one into the neighbourhood of Toulon. The broad and 

 majestic river, winding along the extensive plain, and traversing 

 the continents of the world, conveys to the distance of many 

 hundreds of miles the seeds that may have vegetated at its 

 source. Thus the southern shores of the Baltic are visited by 

 seeds which grew in the interior of Germany, and the western 

 shores of the Atlantic by seeds that have been generated in 

 the central forests of America. 



The marine currents even carry seeds over the broad bosom 

 of the ocean from continent to continent. Fruits indigenous to 

 America and the West Indies, such as that of the Mimosa scan- 

 dens, the cashew-nut, and others, have been known to be drifted 

 across the Atlantic by the Grulf-stream on the western coasts of 

 Europe, in such a state that they might have vegetated had the 

 climate and soil been favourable. Among these the Guilandina 

 bonduc, a leguminous plant, is particularly mentioned as having 

 been raised from a seed found on the west coast of Ireland. 



On the shores of Orcadia, a sort of fruit commonly known by 

 the name of Molucca or Orkney beans are found in large 

 quantities, particularly after storms of westerly wind. These 

 beans are the produce of West Indian trees, and find their way 

 from the woods of Cuba and Jamaica by means of the Gulf- 

 stream. 



As the seeds destined for long aerial migrations are light, and 

 frequently furnished with wings or with downy and feathery 

 appendages, thus the seeds of the littoral plants, whose dispersion 

 chiefly takes place through the instrumentality of aqueous 

 agents, are generally provided with hard water-proof shells, so 

 that they may be wafted over the vast ocean without losing their 

 germinating power. Islands, moreover, and even the smallest 

 rocks, play an important part in aiding such migrations ; for 

 when seeds alight upon them from the atmosphere, or are thrown 

 up by the surf, they often vegetate and supply the winds 

 and waves with a repetition of new and uninjured crops of 

 fruit and seeds. These may afterwards pursue their voyage 

 through the air or along the surface of the sea in the same 

 direction. The number of plants found at any given time on 



