IN BORNEAN FORESTS 



[chap. 



blage of forms of wide geographical distribution, coming from 

 diverse regions and with little or no affinity with each other. 



The fruits of most of the Dipterocarps have wings, which at 

 first sight might be considered most efficacious in carrying them 

 far from the parent plant ; but in point of fact this is not so, for 

 the seed is usually too large and too heavy to allow the flying 

 apparatus to act properly. 1 



Having found in so limited an area so large an agglomeration of 

 allied species belonging to the same genus, and so many representa- 

 tives of various genera belonging to the same family, I am led to 



Fig. 21. — flowers of Palaquium optimum (enlarged). 



the conclusion that the part of Borneo where all these Diptero- 

 carpese are assembled has been a creative centre in the formation 

 of species, and that these have remained on the very spot where 

 they were first formed. It appears to me presumable that a flora 

 must be the richer in endemic elements the more the land on which 



1 If some of the Bornean Dipterocarpeae have a relatively wide geographi- 

 cal distribution, they are species which live near water (Isoptera Borneensis, 

 Scheff., Dipterocarpus oblongifolius, BL), in which the wings may 

 possibly serve as navigating organs. 



02 



