82 



found by Treub on the beach had probably been introduced 

 by ocean-currents, as the original littoral flora in all likeli- 

 hood was quite destroyed. Whether the plants seen in 1886 

 in the interior had been introduced and, if so, in which 

 manner, is fully unknown; it is possible but by no means 

 proven. Which part man, animals, water and wind have 

 taken in a possible introduction of plants into the interior is 

 quite obscure. The investigations of Treub have not at all 

 proven that any fruits, seeds or fern-spores were introduced 

 by wind across the sea. 



5. Treub found in 1886 on Krakatao already 3 plant-associations 



(see p. 70). The total number of species found by him in 

 Krakatao amounted to 34. But many more species may have 

 been present in the is/and of \\ hic/i lie investigated only 

 a very small part. Nothing is known on the flora of the 

 rest. Unhappily this rest comprises the parts most important 

 for the solution of the problem: those higher ravines on the 

 south- and the eastern side, from which the covering layers 

 had soon been removed. Consequently our knowledge of 

 the vegetation in 1886 is very imperfect and can never 

 serve as a base of comparison with the results of subsequent 

 just as defective investigations, which were, moreover, often 

 carried out in other localities. 



6. We know but very little of the vegetation of the localities which 



Treub did investigate, even when we take for granted 

 that this savant really saw and recorded a/1 species of plants 

 growing there, even very young seedlings, which is next to 

 impossible. Treub does not state which ferns formed the 

 main-vegetation and which were rare, neither does he record 

 on which kind of soil the different species occurred. He says 

 nothing of the degree of weathering, the amount of water 

 and the temperature of the soil at different depths, nothing 

 of the composition of the ground-water, nothing of soil 

 micro-organisms, nothing of the extension of the subter- 

 ranean and superterranean parts of the plants, nothing of 

 the fauna and its relations to the flora. Therefore it is 

 impossible to form a clear idea of the vegetation, one only 

 obtains a misty general impression of the whole- 



