ix] THE AGE OF BORXEAX TREES 



which often came in my thoughts during my solitary wander- 

 ings in and around Mattang, and I ultimately came to the 

 conclusion that the great majority can hardly be long-lived ; for 

 they grow very rapidly and continuously all the year round on 

 apcount of the warmth and equability of the climate. As no 

 periodical rest in vegetation occurs in Borneo, the trees which 

 grow there do not show in a transverse section of their trunks 

 those regular concentric rings or zones which elsewhere allow an 

 approximate evaluation of the age of the individual. But it is 

 presumable that the age of Bornean trees is never very great, and 

 cannot be reckoned at many centuries. An argument in favour of 

 this supposition is the great facility with which even arboreal 

 vegetation appears to renew itself in that country, as the many 

 dead and rotten tree-trunks found lying on the ground in the forest 

 amply prove. I found on one occasion a large tree with a trunk 

 about three feet in diameter, almost completely decayed, yet stand- 

 ing upright, its roots still in the ground in the position they had when 

 living, covering completely and surrounding the trunk of another 

 tree of about the same size as the first, which was lying prostrate and 

 rotten. Xow, evidently the time required by the yet standing tree 

 to grow, die, and rot had not been sufficient to decompose entirely 

 the fallen one, which was dead and prostrate when the other grew up. 

 Considering the rapidity with which even the most durable 

 timbers decay in the tropics, I cannot believe that the dead and 

 prostrate trunk could have been there a very long while, as I should 

 certainly have believed had I found in my own country the trunk 

 of an oak of similar size in like condition. 



Again, the abundance of tree-trunks lying dead in the forest 

 shows that the life of forest trees is relatively brief in the tropics, and 

 proves that there arboreal plants are being continually replaced and 

 renewed. The accumulation of vegetable detritus produces the 

 humus which is found in all densely wooded areas, where water 

 cannot wash it away. In tropical forests the humus accumulates 

 in an extraordinary degree, and it can be asserted that in Borneo, 

 and in countries under analogous climatic conditions, the richness 

 and nature of the plants which cover the ground is a direct effect of 

 its depth and quantity. 



Amongst the flowering plants whose existence depends on the 

 humus are certain saprophytes, diminutive plants which possess 

 the means of absorbing the substance required for their nutrition 

 directly from the humus, without the necessity of leaves or of 

 chlorophyll. Of this group, leading an existence very similar to 

 that of the fungi, which they not infrequently resemble in aspect, 

 Mattang possessed a goodly series. Several turned out to be new 

 and of great interest to the botanist ; and sundry forms of slender 

 and transparent Thismias, filamentous Triuridecz, and various 



in 



