P. MACNAIR ON THE ALPINE PLANTS OF PERTHSHIRE. 249 
plants, and that, wherever this band of schist rises to a sufficient alti¬ 
tude, there these plants have been enabled to maintain an existence 
in the great struggle which has exterminated them from the plains, 
the hills, and the majority of even our highest summits. 
Sketch Map of Central Perthshire, and Section across Ben Lawers, showing outcrop of Sericite Schist. 
