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supply of oxygen is very small but they are often very conspicuous 

 and striking in the wet swamp woods of the interior. Their 

 presence shows conclusively that there is not sufficient oxygen in the 

 soil for the plants growing there. Again " Livingstone arrives at 

 the conclusion that at least in some bogwater there occur chemical 

 substances which are not in direct relation to the acidity of the 

 water but which act on the vegetation, and it is suggested that these 

 substances may play an important role in the inhibition from bogs 

 of plants other than those exhibiting xerophytic adaptatious " 

 ( Warming). 



The most important factor, or as Warming expresses it " the 

 weightiest cause of the physiological dryness of the soil lies in the 

 humic acid and other dissolved substances which chemically affect 

 the roots. Humous acids depress the roots activity, and render it 

 more difficult for the plant to replace the water lost by 

 transpiration. " 



It may be pointed out, too, that these lands where this soil 

 formation occurs are quite flat and consequently fully exposed to 

 winds when cleared of forest for planting. In fact one feels the 

 wind sweeping through the cleared ground and sees the seedling 

 rubber plants bending and quivering before it. Now wind has more 

 than one injurious effect on young plants exposed to it. Constantly 

 moving the stem of a young plant, it keeps it loose in the soil and 

 breaks the rootlets and root hairs as they grow, so checking the 

 growth of the plant. But wind also does more. It increases the 

 loss of water by transpiration. The loss of water would be 

 sufficiently bad if the plants were protected from wind, but when by 

 clearing the forest the loss is increased by the exposure to the action 

 of the wind what chance has a hygrophytic plant like Para-rubber of 

 existing? The injurious action of wind in increasing the loss of water 

 has been overlooked or not realised by planters who bare every hill 

 top overlooking the estate to plant more rubber on it instead of 

 leaving windbelts to check this loss of water in the young plants. 

 It is probable that this loss of water by transpiration is the cause of 

 that peculiar wrinkled appearance of rubber leaves that one so 

 constantly sees in wind-swept young plants, but this requires 

 further investigation. Hevea braziliensis possesses none of the 

 adaptation for living in a dry or zerophytic region. Plants adapted 

 for such a region are often protected from excessive loss of water by 

 having the lower leaf surface covered with wax or hairs, by having 

 a thick cuticle to the leaves, by having narrow leaves or leaves so 

 arranged as to present the narrowest surface to the air and in various 

 other ways. The leaves of Para-rubber are thin, neither protected 

 by hair or wax; they are broad and flat, so as to get the freest 

 transpiration in their normal habitat, dense damp shady forests. 

 By planting them on ground where the transpiration or loss of 

 water is excessive, as in these peat lands, we submit them to the 

 same state of affairs as if we planted them in the desert. When we 



