214 



DISPERSION OF 



Aided also by this, the Dandelion, a native of Europe, 

 has diffused itself over every part of our country ; 

 neither impeded by the broadest rivers nor intercep- 

 ted by the loftiest mountains, it has already passed the 

 Allegany and become a tenant of the woods of Ohio. 

 The minuteness of some seeds facilitates their disper- 

 sion by the wind, and it is found that those which are 

 most minute are most extensively diffused. It is 

 chiefly on this account that Mosses and Ferns are more 

 widely scattered than those whose seeds are large. 

 Swartz found in Jamaica the same Moss which he had 

 been accustomed to gather when climbing the mountains 

 of Europe, and there too the same Ferns which he had 

 frequently seen in France, though the other plants 

 were all new and peculiar. 



Indeed, it seems that there is no place so remote, but 

 seeds like these are capable of reaching it ; no moun- 

 tain so high, but they lodge on its very summit ; no 

 cavern so deep, but they penetrate its unmeasured re- 

 cesses ; where, surround >d by many impediments to 

 vegetation, they germinate, and at last fill the atmos- 

 phere with the seeds of another race. 



When the seeds of Balsamine are ripe, the capsule 

 suddenly opens, and scatters its contents abroad ; and 

 the seeds of the common Crane's-bill are thrown to a 

 distance, by the elasticity of the beak, to the base of 

 which they are attached. 



The seed-vessels usually open when the atmosphere 

 is dry, and the sky unclouded, that no vapour may 

 collect on the wings of the seed, and impede its pro- 

 gress. B.:t to this rule the Ice-plant furnishes a re- 

 markable exception. The ornament of a sandy desert, 

 where few other plants are capable of existence, its 

 seeds would be planted in vain, if at an untimely sea- 



