70 



proof that the vegetation of these higher parts also consisted almost 

 exclusively of ferns; on the contrary it is possible that there from 

 rests of the old vegetation a new flora had developed consisting for a 

 large part of Phanerogams. Just as little is known of the vegetation of 

 the lower parts of the south and east side of Krakatao; it is quite 

 possible that a large number of higher plants were growing there. 

 It should always be borne in mind that Treub examined only a very 

 small part of Krakatao, which differed from the rest of the island 

 by the presence of basaltic rocks soon laid bare. Probably nowhere 

 else in the lower parts the covering layer had so soon disappeared. 

 The permanently and deeply covered parts on the south and east side 

 had to receive a new vegetation which could most easily come from 

 the higher parts of those ravines from which the covering layer had 

 been washed away very early (See pp. 20, 21). It is unknown which 

 plants were growing in 1886 in these ravines and it is just als little 

 known which plants occurred on the southern and eastern lower part 

 of Krakatao. They may have been Cryptogams, they may have been 

 Phanerogams, probably both. Nobody knows anything about it! 



For sure we only know that Treub in the restricted locality 

 examined by him found a vegetation of kremnophytes, mainly ferns. 

 Not P e n z i g in 1897, as Docters van Leeuwen supposes '), 

 but Treub in 1886 was the first who found in Krakatao a plant- 

 association or, more exactly speaking, already three; one association 

 of algae and two of higher plants: on the beach a very poor one, 

 for the main part composed of introduced halophilous Phanerogams; 

 in the interior a richer one, mostly of heliophilous kremnophytic ferns, 

 perhaps originating for the greater part from surviving components 

 of the old vegetation. 



That in the investigated locality Phanerogams occurred only in 

 scattered specimens between the ferns is quite naturally explained 

 by the fact that in these parts of the Dutch Indies there is a much 

 higher percentage of kremnophytes among the ferns than among 

 the higher plants. Of the 42 kremnophytes of the lower regions 

 recorded on p. 31 as many as 29 are ferns or fern-allies. Moreover, 

 under circumstances, ferns can, by their spores, reproduce themselves 

 easier and sooner than Phanerogams which often need the help of 

 animals for the pollination of their flowers or for the dispersal of 

 their fruits or seeds. The fauna of Krakatao in 1886 being quite 



1 ) Handelingen Eerste Nederlandsch-lndlscli Natuurwetenscliappelijk Congres (1920), 

 p. 'iS.-Annales |ard. Bot. Buitenzorg XXXI (1921), p . 115. 



