63 



From his finds Treub drew a series of conclusions numbered 

 by me from 1 to 9. On each of these I state my views here- 

 beneath. 



/. The flora of the interior of Krakatao entirely differs from that 

 of the beach. 



Apparently this fact is emphasized by Treub because he 

 considers it as contrary to his original opinion 1 ) that the new 

 vegetation of Krakatao, like that of a very young coral island, would 

 originate from seeds washed ashore and would consist mainly of 

 littoral plants. Many such plants, as Treub could have observed 

 in the Buitenzorg Botanical Gardens, may prosper at least when 

 cultivated far from the sea and at a rather considerable altitude-). 

 Hence it might be expected that on Krakatao they would be able 

 to penetrate to a rather large distance from the sea. But there is a 

 great difference between Krakatao where, in consequence of leaching 

 caused by the large rainfall, the higher layers of the soil in the 

 inclined localities soon became salt-free and a very young and 

 small level coral island which consists, so to say, entirely of a young 

 beach, hence contains much salt, does not possess in its centre a 

 basin of sweet water (stored rainwater) and therefore can bear only 

 a halophilous vegetation. On the beach of coral islands as well as 

 on that of Krakatao seeds and fruits of all kinds of plants may be 

 washed ashore and the lighter ones of these, after having dried during 

 the low tide, may by the sea-wind be driven into the interior. But in 

 the interior of a very young coral island the seedlings of halophytes 

 only can remain in life; the other ones soon perish in consequence 

 of the large salt-percentage of the soil. In the interior of Krakatao 

 the seedlings of non-halophytes also can develop. The occurrence of 

 halophytes in the interior depends on many conditions, apparently not 

 only on competition with other plants or the mode of dispersal of the 

 seeds. In Java many littoral plants (i.a. Albizzia retusa Bth., Euphorbia 

 Atoto Forst., Guettarda speciosa L,,~ Pemphis acidu/a Forst., Ponga- 

 mia pinnata Merr., Scaevola frutescens Krause, Sophora tomentosa 

 L., Spinifex littoreus Merr.,~Thespesia populnea So/and, and Tribulus 

 cistoides L.) are in a wild state never found at a distance worth 

 mentioning from the sea, not even when the locality behind offers 

 plenty of space; neither are these species ever found in saline localities 

 in the interior where some other halophytes of the coast (Acrostichum 



1 ) Ann. |ard. Bot. Buitenzorg, Ime Serie VII (1888). 216. 



2 ) Buitenzorg lies at about 250 m. above sea-level. 



