100 HUMUS AND THE DEFERTILIZATION 



that almost entirely compose it. Now, why should there be 

 this difference between the forests of this class and the pre- 

 ceding ones? The casual observer is easily able to account 

 for the want of humus in deciduous forests. It is all burnt 

 up annually he says, how then can there be humus ? No 

 doubt forest fires burn up every particle of dry vegetable 

 matter they can get at ; but if a forest at a low elevatien 

 were protected from fire for a century, there would still 

 be no humus ! 



Annually the trees of deciduous forests shed countless 

 millions of leaves on the surface on which they grow. 

 Their dead branches and trunks fall, and rot where they lie 

 (if not burnt up) and yet there is no humus ! Countless 

 hosts of insects are at work carefully collecting and bury- 

 ing every particle of vegetable matter, that is devoid of 

 life. Every leaf and twig that falls is instantly covered 

 with a layer of earth by the teeming millions of white ants 

 (Termes) that inhabit all tropical countries, and carried 

 piecemeal deep into the earth. Every tree that dies or 

 falls is bored into and reduced to powder by other countless 

 hosts of longicorn and other beetles, everything being sub- 

 sequently buried by the termites in their galleries from two 

 to twelve feet underground. In course of time other myriads 

 of earthworms devour the vegetable substances thus hid- 

 den, with quantities of the finer particles of the soil, which 

 they throw up to the surface of the soil in the shape of 

 what is known as worm " castings." 



Thus the leaf mould is not lost but only hidden from 

 sight, to reappear in a different form on the surface of 

 the soil. 



But in the deciduous forests the fall of leaves is so very 

 sudden that the white ants have but little time to collect 

 the harvest before the forest fires devour it. Instead 

 therefore of the leaves, twigs and trunks returning to the 

 soil, what was taken from it for their formation!, they are 

 burnt to ashes which the winds of heaven and April storms 

 carry far and wide. Ill the course of centuries and centuries, 



