viii INTRODUCTION 
the work, by which the volume has so greatly 
benefited. 
I have now the pleasing task of recording my 
gratitude, in the first case, to my wife, who read 
the whole of the manuscript, and, in the second case, 
to Mr. John Ramsbottom, Secretary for Botany, 
Linnean Society of London, who read it in proof; 
from their helpful emendations the present volume 
has gained immeasurably. 
B. D. J. 
