28 ON FARLETON FELL 
the still remote time—as measured by human 
standards — when the plants which now grow 
appeared on the Earth’s surface, we may try, from a 
study of their present distribution and of the dis- 
tribution of their remains in regions where they are 
no longer found living, to determine their area of 
origin, and to trace the date and course of the migra- 
tions by which they reached our country. In the 
case of the British Isles, geological considerations 
play a leading part in such investigations, these 
islands being but outlying hummocks of a great con- 
tinental area, at times joined to the main land-mass 
by a slight upward movement of the Earth’s crust, 
and anon cut off from it by a movement of depres- 
sion. In this connection also we may be led to in- 
vestigate the means by which plants spread, and 
especially their capacity for crossing barriers of the 
various kinds indicated in our brief study of deserts 
in the previous pages—the serious barriers offered 
by water-channels, or others equally difficult to nego- 
tiate produced by areas of uncongenial soil, by 
mountain ranges, or by forests. This will involve 
especially a study of seeds and the interesting phe- 
nomena of seed-dispersal. 
Again, the most popular branch of botanical study 
in England is Floristic Botany, which traces the dis- 
tribution within our area of the various species com- 
posing its flora; and with it is necessarily associated 
a study of the plants themselves so far as the char- 
acters are concerned, by which they may be dis- 
tinguished from each other. This last is the province 
of Descriptive Botany. The study of local distribu- 
tion, if conducted intelligently, will greatly assist in 
