( 706 ) 



I tliiiik it however more probable, tluit in the Ciise of this species, 

 as ill that of the next one, [Dodonaea viscosa) such large winged 

 fruits have been and are still, only transported in 

 stages. It may have been, that in former times other climatological 

 conditions enabled these two species to grow wild in the 30—40 

 kilometres of intervening low lands, in such places where growth 

 can no longer take place at the present time. It may also be that 

 even under the present conditions of climate, isolated specimens have 

 escaped notice and might be found between the two places so far 

 apart. Finally we may suggest, that transport by wind does not 

 primarily take place through the air direct, but chiefly in stages, 

 in such a way, that the fruits remain for a longer or shorter time 

 on the ground, or floating on the surface of water; in the latter 

 case of course, till they are washed ashore and are then carried 

 further by the wind. 



The original occurrence across the sea of this Acer growing wild 

 in Java and provided with fruits, which are apparently only adapted 

 for wind transport, may, it seems to me, be readily explained by a 

 combination of wind transport in stages with transport by water, 

 but not exclusively by so called direct wind transport. This expla- 

 nation possibly also applies to other species, growing in Java and 

 belonging to other genera or orders, with physiologically similar 

 fruits or seeds, which have hitherto only been regarded as anemophilous. 



It should further be noted, that this species only bears fruit at an 

 advanced age, when the crown has already attained a considerable 

 height. This character is perhaps useful, since the tree generally 

 occurs scattered in dense ever-green heterogeneous mountain forests, 

 composed of high trees. For this species, wdiicli is obvioirsly in the 

 main dependent on wind distribution, the above-mentioned character 

 is probably connected with the oecological conditions determining the 

 original occurrence of the tree, and the character referred to, has 

 arisen through natural selection. For in the damp Javanese mountain 

 forests, which are generally very dense, only those species have a 

 good chance of being disseminated by the wind, whose fruiting 

 branches i)rotrude above the dense leaf covering, formed by the 

 crowns of the surrounding trees. 



In connexion with tlie obvious relation between the conditions of 

 growth, the fruiting period and the means of dissemination of Acei^ 

 niveuin, we may quote what has been said by Vogler ') on a similar 



1) VoGLER, P., Ucber die Verbieitungsmittel der Schweizerischen Alpenflanzen in 

 Flora Oder allg. botan. Zeitung 89 (1901) p. 2. 



