8i 



planting nutmegs and betel-nuts so high, on the hills that the denuda- 

 tion not only brought down so much soil on the fields at the base of the 

 hills that they were put out of cultivation, but all the remaining trees, 

 forest or cultivated, on the upper part of the slopes were falling down 

 the hills. Nothing of the kind had occurred of course till the lower part 

 of the slope was cleared for cultivation as the steepest hills in the 

 peninsula have always been covered with a dense forest of high trees 

 where the ground has been cleared and planted on a steep slope. In 

 these places, the Malays and Chinese terrace the hill so as to prevent 

 the loss of their nutmegs and clove trees by the denuding away of the 

 hill. I have not seen this done in any rubber estate yet, though I 

 have seen a good many in which it will be necessary, soon or later, 

 to do so in order to save the trees. 



In more level places, if the ground is covered with turf the 

 denudation is reduced to a minimum, the formation of humus over- 

 lying the stiff yellow clay on which the turf has been placed shows 

 this very clearly in a few years. Indeed, the colour of the water 

 running off a turf slope in a rainstorm compared with that of a water 

 rush off exposed ground shows this very clearly. In the former case, 

 the water is nearly transparent, in the latter opaque, yellow or red. 

 In covered ground, after a heavy rain, the springs in the hill become 

 overfull and the water perfectly clear and pure is poured out at vari- 

 ous points. All this water which has fallen upon the covered ground 

 has soaked in and has not run off the surface denuding it. 



The regular fall of leaves from the trees should form the humus 

 of the soil and as they decay go back to form food for the trees, 

 but the light fragments and the soluble salts produced by the 

 decay of the leaves and twigs are naturally the first to be carried 

 away by a rainstorm, causing a considerable loss to the plantation. 

 In the case of ground covered with herbage, the loss in this way is 

 trivial, for in the first place the creeping stems and leaves of the 

 grasses hold the fragments of half-decayed leaves and sticks and 

 secondly the soluble portions are mainly carried out into the 

 ground by the water soaking through the turf and applied to the tree 

 roots. 



In England, on the other hand, in ordinary fiat ground the soil 

 gradually rises under turf or herbage as has been shown in Darwin's 

 ** Vegetable mould and earthworms," and this is mainly affected by 

 earthworm.s, which, as has been shown, are valuable tillers of the soil. 

 Earthworms, however, in the Malay Peninsula are rare, and only can 

 he found in damp lowlying spots to where termites cannot live. 

 They cannot indeed compete with the termites for the decomposing 

 twigs and leaves which form the food of both animals. The termites 

 do not form a good substitute here for earthworms. They do not 

 turn over the soil at all except by occasionally throwing up a mound 

 of clay shortly before they assume the winged stage. On the other 

 hand, they appear to destroy the vegetable debris without converting 

 them into humus (See Bulletin, old Series p. 77). 



