GEOGRAPHICAL DISTRIBUTION OF PLANTS. 165 



but I must advert to the fact, as strikingly in har- 

 r mony with my hypothesis of development, which 

 was certainly formed without any knowledge of 

 this illustration. 



Another mode of proof in the difficult circum- 

 ' stances with which we are dealing, is to show that 

 [ the hypothesis will account, on a principle of law, 

 \ for certain facts which we must otherwise suppose 

 Ito be wholly capricious and accidental. The 

 hypothesis is, that, as a general fact, the progress 

 of being in both kinds has been from the sea to- 

 wards the land. Marine species of plants and 

 animals are supposed to be, in the main, the pro- 

 genitors of terrestrial species. Life has, as it 

 were, crept out of the sea upon the land. This of 

 cotu'se leads us to consider the distribution of 

 vegetable and animal forms in the sea, and the 

 effect which these may have had in determining 

 the Flora or Fauna of particular detached pro- 

 vinces. We would necessarily suppose that any 

 particular Flora or Fauna occup\'ing a certain 

 geographical area in the ocean, would be apt to 

 become the common source of the Flora or Faima 

 of any masses of land adjoining to it. Now we 

 shall see how the facts harmonize with this view. 

 Wherever there is a group of islands standing 



