viii PREFACE 



arguments brought up mostly assumed that the older theory was 

 sound, the writer's faith remained unchanged, and he continued 

 to follow up his beliefs. They are now yielding interesting results, 

 of which the present book is one, while another, dealing with 

 distribution, and whichis perhaps even more subversive of current 

 opinions (used as a shelter for so much in national policies), is 

 upon the road to completion. 



The present book, the logical sequence of Age and Area, has 

 been greatly delayed by various inconveniences, and by the great 

 quantity of statistical work required. This was so great a burden 

 that I can hardly sufficiently express my gratitude to my friend 

 Mr John Murray, late of the Indian Educational Department, 

 who undertook a great deal of it, and with his trained mathe- 

 matical skill was able to do it well and rapidly. I am also deeply 

 indebted for aid to Dr W. Robyns, Director of the Botanic 

 Garden at Brussels, Dr B. P. G. Hochreutiner, Director of that 

 at Geneva, and Sir Arthur Hill, Director of that at Kew, at all 

 of which places, and especially the first named, I have done 

 much work. My friend Mr G. Udny Yule has helped me very 

 greatly with criticism and assistance, and I am also much indebted 

 for help to Mr J. S. Bliss, Dr C. Balfour Stewart, and many 

 others. 



J. C. WILLIS 



LES TERRAGES 



AVENUE DES ALPES 

 MONTREUX 



25 March, 1940 



