283 



Mr. Docters van Leeuwen predicts that ,,the mixed forest 

 ,,will eventually develop into the complex old wild-forest". If by this 

 singular prophecy it is meant that the present forests of Krakatao 

 will get gradually older and richer in species, I can agree with him. 

 But I also think that there is no need for further investigations on this 

 difficultly accessible island, Krakatao being for the botanist not more 

 important than any secondary forest on Java which can be invest- 

 igated much more easily and at much less cost. 



9. The single excursion to Sebesy yielded (in 6 days) 359 species whilst on the 

 many Krakatao-excursions 259 were collected. It should be, borne in mind 

 that on Krakatao man has played a very modest part as a transmitter and a 

 much more important one on Sebesy. 



In the second appendix to Mr. Docters van Leeuwen's 

 paper there are indeed enumerated 259 species of vascular plants 

 for Krakatao and Verlaten Eiland together, but it does not appear 

 which of these species were collected on Krakatao itself. Of the 

 part man has played on Krakatao as a transmitter" nothing definite 

 is known, though it is probable that at least the 13 ruderal weeds 

 found for the first time in 1919 were introduced by man or his 

 domestic animals. Other plants also, f.i. Cocos nucitera, Carica 

 papaya, Citrus, may be quite well have been introduced by human 

 intervention. 



10. On the plant associations of Krakatao the following remarks may be made: 



a. As to the littoral vegetation: nearly all these plants belong to the typical 



beach-plants; this vegetation covers d very large area and is accordingly 

 very rich in species and in individuals. 



b. the Karringtonia formation is confined to very narrow belts behind the first 



zone of plants. 



c. the Cdsuar/Via-formation is found in several places mostly already fairly old 



with few rejuvenated parts. Little forests are found dotted about on top 

 of the old ash- layer more than 80 feet above the sea; a proof of the fact 

 that the seeds may be spread not only by the sea-currents but also by winds. 



d. A Mangrove-vegetation does not exist at all. 



e. the Savanna or grass-vegetation is still everywhere to be found on the hills 



of Krakatao but in several places and especially in the ravines it has been 

 entirely ousted by a very young forest consisting of a very few species 

 of trees. Especially Macaranga tanarius M. A. has an important effect in 

 strangling a grass-vegetation. The seeds of this species of tree were found 

 in the intestine of a bird, Calornis strigatus Horsf. (= C. chalybea Horsf.) 

 shot on Krakatao in April ! 91 9. These very seeds were sown by Mr. Docters 

 van Leeuwen in the Buitenzorg garden and grew up into specimens of 

 this tree. Ficus species and Pipturus incanus Wedd. occur numerously in 

 these groves, 



