177 



With these views I can only partly agree. It is not proven that in 

 former years the entire south-eastern part of the island bore a fern- 

 vegetation like that which Treub and Penzig found on the basaltic 

 rocks of Zwarte Hoek. It is highly improbable that the basaltic rocks 

 will ever bear a forest, that littoral plants ever ran high up against 

 the mountain, that the young forest of the interior has originated 

 from the littoral one. The trees found at some distance from the 

 beach belonged in 1906 exclusively to such species as are never 

 found on the beach proper and those parts of the ravine-forest 

 between 200 and 400 m. above sea-level which were reached in 1908, 

 did not contain a single littoral species. On p. 26 I argued already 

 that in my opinion it were the higher ravines which formed an im- 

 portant starting-point for part of the new vegetation. Of course I 

 will by no means deny that introduction from outside the island 

 might in 1906 already have taken place with plants of the interior, 

 but all data required for drawing a safe conclusion on this point 

 are lacking. 



