216 A. G. HAMILTON. 
and offal) for which again there is little or no return. This enor- 
mous drain cannot go on without affecting the plant bearing 
capacity of the soil. 
With regard to the second head—the substances added to the 
soil, they consist mainly of excreta and the dead bodies. Human 
excreta and bodies as at present treated may be considered as 
making no addition, and those of animals very little, the latter being 
as a rule scattered over wide spaces. But even so, a greater pro- 
portion of the droppings of sheep reach the soil now as compared ~ 
with the old days when the animals were shut up in yards ten or 
twelve hours out of every twenty-four. Then nearly half the 
manure accumulated in the yards; and people who recall the 
system must have a lively recollection of the state of these sheep- 
folds when used for a long period. Certainly some of the manure, 
dissolved by rains and carried away in surface water by the fall of 
the ground, did reach the vegetation again, but only to a limited 
extent, and on a restricted area. 
The amount of change produced in the local flora by the addition 
of substances derived from the excreta, or dead bodies of intro- 
duced animals may fairly be regarded as so small as not to be 
worthy of consideration. 
(c) Spreading new plants by the introduction of new animals. 
This is a very potent factor in the alteration of the native 
vegetation but will be best considered in Division ITI. 
Second Subdivision—TZhe destruction of native fauna or its modt- 
fication altering vegetation. 
(a) Direct destruction of the native fauna and its effects. 
The amount of destruction wrought among the native animals 
by settlement has undoubtedly been very great. Many animals 
and birds have become very scarce, and are only to be found in 
sequestered spots. And we may expect from the experience of other 
countries, that in time, a portion of our fauna will become extinct. 
As cases in point the buffalo in North America, the dodo and 
solitaire in Mauritius, and nearer home, the Nestor parrot of 
