ALPINE PLANTS. 5 
placed in a condition unfavourable to their 
growth. 
We cannot fail to perceive from these facts 
how much depends on how the proper pro- 
portions of earthy and vegetable constituents 
are mixed together. 
Hence the value of proper mixtures (referred 
to in the book) will be very apparent, as thus 
the roots are preserved from compression and 
a free access of air is permitted. 
Thus it is that different plants want different 
soil and treatment (referred to later), and each 
plant grows well where its wants can be fully 
and most easily supplied; as they do not 
possess the power to move from place to place 
independently, we must by artificial means 
minister to their most important needs. 
Here I may add a word about top-dressing 
rockeries and how it should be done. 
As I have previously mentioned, the access 
of air is most essential, therefore, before top- 
dressing is commenced, the whole surface 
should be worked up with a fork, so as to 
lighten the soil and give free access of - 
air; then the top-dressing may be com- 
menced, taking care to work backwards (so 
