58 FOREST CULTURE AND 
of tree or other plant, inasmuch as necessarily the per- 
centage must fluctuate according to the nature of the 
soil, this, again, depending on geologic structure and 
the quality and quantity of decaying foliage on any 
particular spot. It should, however, not be quite for- 
gotten that most plants have a predilection for that 
soil which contains, in regions otherwise favorable to 
them, also due proportions of such mineral particles as 
are essentially necessary for the normal nutrition of 
the peculiar species ; for, otherwise, in the wild com- 
bat for space it would succumb or cede before the 
more legitimate occupant of such soil. Hence, at a 
glance, even from long distances, we may recognize 
in many of our forest regions an almost abrupt line 
of demarcation between the gregarious trees, where 
one geologic formation meets or replaces the other. 
Thus, trees richer in potash, or oils, or any other 
product, may often be traced with ease over their 
geologic area, for which purpose the admirable maps 
of Mr. Selwyn and his collaborators afford us here in 
Victoria also in this respect already so very much 
facility. 
I have often been led to think that many an indi- 
gent person might find employment by collecting the 
wood-ashes, which, as a powerful manure, or as ma- 
terial for a local potash-factory, ought to realize a fair 
price. Such an employment would be probably as 
lucrative as collecting glass, or bones, or substances 
for paper-mills, while the ashes, now largely wasted, 
would be fully utilized. 
It may be assumed that, at an average, the ash of 
our ordinary Eucalypts contains ten per cent. of crude 
potash, equal to about five per cent. pure potash. A 
