11 



is no reason why they should not have done so afterwards. By these 

 people also plants may have been introduced, either accidentally 

 or purposely. That Cocos nucifera was introduced in this manner is 

 out of doubt (Cf. Chapter IV.). 



One mostly is inclined to exaggerate the share which the wind 

 takes in the transport of seeds and fruits across the sea. Anyhow, 

 not for a single one of the species occurring at present on Krakatao 

 it has been proven that its spores, seeds or fruits were carried over 

 by wind, though for the minute spores of Cryptogams and seeds of 

 orchids I will by no means deny the possibility of this conveyance. 

 One should bear in mind that, by land, seeds and fruits are much 

 more easily carried over long distances by wind than across the 

 sea. On land, where light objects after having dropped, may be 

 swept up again by every strong gust of wind and where the wind 

 has often a more or less upward direction, due to obstacles in its 

 way, strong and continuous air-currents can probably convey very 

 light seeds and fruits over long distances. But this does not hold 

 good for transport across the sea. Seeds and fruits fallen into the 

 water can no more be carried upwards but either remain floating on 

 the surface or sink to the bottom. In the former case further convey- 

 ance can only take place by sea. In the latter case they are lost 

 unless they happen to fall into the water quite near the coast, where 

 they may be washed ashore. Transport of seeds and fruits of some 

 weight by wind across a water-level can therefore practically be 

 made only in a single flight: that this has happened in the case of 

 Krakatao, vid. over a distance of more than 20 km., has never yet 

 been proven. The reality of this transport, however, has always been 

 considered an axiom. Rightly D i e I s ') observes: ,,Dasz der Phantasie 

 ein groszer Spielraum bleibt, auch betrachtlichere Entfernungen auf 

 diese Weise iiberbriickt zu sehen, bedarf keiner Erwahnung und 

 bestatigt sich in der Literatur". The presence of ferns and Compos/toe 

 on Krakatao is by no means conclusive evidence for transport by 

 wind as I will show in my discussion on the paper of T r e u b. 



Transport of light seeds, which different authors on the flora of 

 Krakatao have ascribed to the action of winds, might in many, if 

 not all, cases have been as well made in another manner. Numerous 

 fruits, seeds and spores either fall directly into watercourses or are 

 carried along to them by rain-water flowing rapidly over the ground 

 during the heavy showers which are so frequent in West-Java and 



Prof. Dr. L- Diels, Pflanzengeographie (1918), p. 43, 



