THE CLIMATAL DISTRIBUTION OF BRITISH PLANTS. 49 
abundant on some of the moors of West Cornwall; then 
a large number, although by no means universally distri- 
buted, are yet found throughout the greater part of the 
country, and I could give examples showing every gradation 
from great rarity to universal distribution. 
This subject of the distribution within Great Britain of 
our native plants may be considered from several different 
points of view. Fivst—The flora may be divided into 
classes according to the parts of the country in which the 
various plants grow, that is, according as they are confined 
to Scotland, the South of England, the Eastern or the 
Western Counties, or are found throughout the whole of 
the country: this is called Topographical Distribution. Secondly— 
plants may be classified according to the soils which they 
require or prefer, this is called Geological or Lithological 
Distribution. However, I shall not deal with either of these 
subjects, the subject of my paper being a third branch, viz: 
Climatal Distribution, by which I mean distribution as affected 
by the differences of climate caused by differences of latitude 
and altitude—how far the plants we are treating on, range 
northwards and southwards throughout the country, and 
upwards and downwards on mountain sides. 
If anyone will, while ascending a mountain, take the 
trouble to make lists at three or four stations on the way 
up, of the plants he meets with at each station, and then 
compare these lists, he will notice that there has been a 
gradual change in the flora during his ascent—plants found 
at the lowest station are absent from the second, while a few 
kinds not found in the former have now made their appear- 
ance. Again, comparing the third list with the second, and the 
list of plants found on the summit with the third, similar 
changes will be noticeable. Finally, let him compare the 
list made at the summit with that made at the starting; 
the plants whose names occur in both lists will be very 
few. 
