of Edinburgh, Session 1884-85. 
145 
or in the lower districts of Africa, this statement may seem an 
exaggeration. But on one range of forest-clad hills on the great 
plateau between Lake Hyassa and Tanganyika I have walked for 
miles through trees, every one of which, without exception, was 
ramified, more or less, with tunnels. The elevation of this locality 
was about 5000 feet above the sea, and the distance from the 
equator some 9° ; but nowhere else have I seen a spot where the 
termites were so completely masters of the situation as here. If 
it is the case that in these, the most elevated regions of Central 
Africa, the termite colonies attain their maximum development, the 
fact is of much interest in connection with the geological and agri- 
cultural functions which they seem to serve ; for it is here precisely 
before the rivers have gathered volume, that alluvium is most want- 
ing; it is here that the tiny head waters of these same rivers collect 
the earth for subsequent distribution over the distant plains and 
coasts ; and though the white ant may itself have no power, in the 
first instance, of creating soil, as a denuding and transporting agent 
its ministry can scarcely be exaggerated. 
The direct relation of the termites’ work to denudation will still 
further appear, if we try to imagine the effect upon these accumula- 
tions of earth-pellets and grains of an ordinary rainy season. For 
two or three months in the tropics, though intermittently, the rains 
lash the forests and soils with a fury such as those in temperate 
climates have little idea of ; and though the earth-works, and 
especially the larger ant-hills, have marvellous resisting properties, 
they are not invulnerable, and must ultimately succumb to denud- 
ing agents. From a geological point of view, these ant-hills, which 
occur in such numbers all over Africa that the whole country may 
be regarded as one vast ant-city, are to be looked upon simply as 
heaps of decomposed rock waiting to be removed from the surface 
of the earth. The tunnels, again, being only required for a temporary 
purpose, are made substantial enough only to last the occasion ; and 
in spite of the natural glue which cements the pellets of earth 
together, the structure, as a whole, after a little exposure, becomes 
extremely friable, and crumbles to pieces at a touch. Many trees, 
from which all the earthy material has been long since swept away, 
still bear upon their trunk and branches the long, irregular stain 
which indicates former termite sites. And although the insects will 
VOL. XIII. 
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