THE PROBLEM 27 
maining parts, though drainage, grazing, and other 
human operations have wrought great changes, the 
face of the country still wears to a large extent its 
ancient appearance, and the flora is still in the main 
that which flourished before human activities began 
to put their impress upon it. 
How are we to set about studying this varied 
vegetation which, in a thousand forms, covers hill 
and valley? There are several avenues of approach; 
any one of them, if explored fully, would take us far 
beyond the limits of the present volume; we shall 
have to be content with slight venturings along 
several of them, so as to acquire, in a brief space, 
as wide a view as we can of the phenomena which our 
flora displays, and of the problems which it presents. 
If we view the vegetation as a whole, we may be 
tempted to enquire first as to its origin and history. 
We know that plants have existed on the earth for 
millions of years, but that the plants of past ages 
were different from those of the present, just as those 
of the present will ultimately give place to other 
forms as yet undreamed of: that the vegetation on 
which we feast our eyes is, in fact, but the momentary 
expression of a never-ceasing process of life and 
change. This is the point of view of the geologist, 
to whom 
The hills are shadows, and they flow 
From form to form, and nothing stands ; 
They melt like mist, the solid lands, 
Like clouds they shape themselves and go. 
Pursuing this line of enquiry, we may endeavour to 
trace the descent through the ages of our present 
plants from bygone types; and coming at length to 
