322 Matthews. — The Distribution of Plants in 
I wish to present deal with the range of dispersal in Perthshire as deter- 
mined by the number of districts occupied. 
For botanical purposes Dr. White ( 1898 ) divided the county of Perth 
first into two primary regions, Highland and Lowland, the area of the 
former being a little more than twice that of the latter. A convenient 
boundary was found in the line of the ‘ Great Fault ’ which runs across the 
county in a south-westerly direction (Fig. i). The Lowland area is further 
subdivided into five, the Highland region into eight districts, the boundaries 
being largely determined by the chief river systems. Within the Lowland 
region, with an area of 842 square miles, only 91 squafe miles are over 
1,000 ft. The Highland region extends to 1,747 square miles, embracing 
1,346 square miles over 1,000 ft., 314 over 2,000 ft., and 17 over 3,000 ft., 
including 89 peaks which each exceed 3,000 ft., the highest being Ben 
Lawers (3984 ft.) in Breadalbane. We are thus dealing with a region pre- 
senting a very varied topography, with edaphic and epedaphic conditions 
which differ according to whether the Lowlands or the Highlands are 
concerned, and whose rivers and mountains present a succession of barriers 
to the migration of plants from one district to the next. If the application 
of the ‘ Age and Area 5 hypothesis throws any light on the distribution 
and migration of plants within this region, it may also prove a useful aid 
