Introduction. 5 
On all these grounds, it will be clearly seen how 
much depends upon the proper blending of earthy 
and vegetable constituents in mixtures of soil, quite 
apart from their chemical character. 
But, if it is necessary to practise a method in 
planting which shall procure proper conditions of 
drainage and porosity of soil, it is no less neces- 
sary that such a method of treatment should also 
regard the living activities of each specific kind of 
plant. 
Different sorts of plant are marked by peculiarities 
of assimilation, and use up distinctive proportions of 
the food-stuffs upon which they live. Hence, as 
plants are unable to move from place to place, 
except by circumferential growth, it is necessary, 
under the artificial conditions of cultivation, to supply 
by appropriate means that renewed provision for 
their continued activities which is brought to them 
under the natural conditions of their life. 
Such a provision is most effectually made by the 
practice of top-dressing, which, in correspondence 
with the sequence of events in a state of nature, is 
best given in autumn, when the flowering season of 
most Alpines is past and that of active growth 
begun. 
It is perhaps hardly necessary to add that this 
work of top-dressing should be undertaken mindful 
of the necessity for free access of air through the 
soil already mentioned. Hence, before this top- 
dressing is begun, the whole surface should be 
worked up with a fork, so as to lighten the soil and 
give free access of air; and then care must be taken 
