adheres to. He adds that the pioneer ferns were only *) such species as were 

 used in their natural homes to ,,open sunlight and a non-waterretaining soil", 

 such as Ceropteris ca/ome/anos Und. and other kinds. Three years after the 

 eruption Krakatao was, at the coast, furnished with littoral plants and more 

 in the interior with algae and ferns. A few grasses and bushes were also to 

 be met with already here and there. Investigations however, have disclosed, 

 that there also are other plants, whose seeds and fruits can float in sea- 

 water for some length of time without losing their germinative power; they 

 also will therefore be washed ashore and can develop as a part of the new 

 strand-flora, but gradually they are killed, choked '-) or ousted by the real 

 beach plants. 



The paper of Treub being already at length discussed in Chapter 

 IV, I need not refute here the general views of Mr. Docters van 

 L e e u w e n. His statement that the pioneer ferns were only such as 

 are used to ,,a non-waterretaining soil" is mast incorrect.- Acrostic/ium 

 aureum L. :i ), Stenoc/i/aena palustris Hedd. /l ) and Pteris tripartite S\v. ') 

 require a marshy, wet, or at least humid soil; Ceropteris ca/orne/anos 

 Und. (> ), Blechnum orienfa/e L.~) and Nephrolepis exa/tata Scholt*) do 

 not thrive in a very dry one. As regards the 3 last-named ferns 

 Mr. Docters van Leeuwen makes here the same mistake as is 

 commonly made by unexperienced collectors; he takes into conside- 

 ration only the surface of the soil, not the layers in which the plants 

 root. As to his description of the plant-covering of Krakatao in 1887, 

 he does not for a moment consider that Treub investigated only 

 a small part of the lower slopes on the north-western side, so that 

 his conclusions need not hold good for the rest of the mountain. 

 As to the non-littoral plants whose seeds are washed ashore and 

 germinate there, but which ,,are gradually killed, choked or ousted 

 ,,by the real beach-plants", Mr. Docters van Leeuwen quite 

 forgets in this explanation to take into account edaphic factors. 

 The true littoral plants are halophytes and grow in a soil unfit for 

 non-littoral species. As I already observed herebefore one has to 

 carefully distinguish between young, salt-containing beaches and old, 

 leached-out ones. And one should also consider that, where the sea 

 rapidly washes away the land, the border of the latter may not be 

 a beach in the oecological sense of the word, and also that many 



1 ) Italics by me. (B). 



2) The English text has here, probably by misprint, chocked. From a comparison 

 with the Dutch text, which uses here the word ,,verstikt" , appears that the right reading 

 is such as given above. 



:1 ) See p. 55, No. 4. 



4 ) See p. 54, No. 2. 



5 ) See p. 59, No. 10. 

 c ) See p. 54, No. 1. 

 7 ) See p. 55, No. 3. 

 s ) See p. 56, No. 6. 



