Chap. VI] EDAPHIC INFLUENCES IN THE TROPICS 



381 



combined with ijrcnt humidit)-. In addition, in tropical districts with 

 a heavy rainfall, on account of the great abundance and intensity of 

 atmospheric precipitations, the organic products of decomposition arc 



3. 



&> 





drained away to such an extent that many tropical rivers, especially during 

 the rainy season, assume a coffee-brown colour. 



Soil rich in humus, with 8-9 7» of organic matter, is found within the 



