CONTENTS 



I'ACE 



tion — Conditions of Flight — The Scoring and Autumn As- 

 pects of Migration in the British Archipelago — Internal 

 Migrations and Local Movements in the British Area — 

 Irruptic Movements — The New Law of Dispersal — Its 

 Bearing on the Arctic, Element in South Temperate Floras 

 — Inter-polar Floras — Impossibility of Emigration of Plants 

 from North to South — Presence of Southern Genera in 

 Europe — The Andes as a Route for the Southern Migra- 

 tion of Plants — The Floras of Mountains in the Torrid 

 Zone during Pre-Glacial Ages — " Arctic " Floras could 

 never have been Developed in the Polar Regions — Dis- 

 persal of Plants North and South from Equatorial Range 

 Bases — Effects of Glacial Epoch on Northern Floras — 

 Absence of many Species from Equatorial Range Bases — 

 The " Retreat " of Plants a Myth — Conditions of Successful 

 Dispersal — The Flora of the Mountains of Asia — Inter- 

 Hemisphere Species — Species in Polar and Temperate 

 Zones — The Distribution of Plants in Africa — The Tem- 

 perate Flora of South Africa — Northern Emigration from 

 Antarctic Centres obviously Erroneous — The Bearing of 

 this New Law of Dispersal on the Absence of Southern 

 Types from the Northern Hemisphere — The Dominant 

 Southern Flora — Its Dispersal from Range Bases south of 

 the Equator — The Problem of Migration and Geographical 

 Dispersal hitherto attacked at the Wrong End — Exter- 

 minating Influence of Glacial Epochs — Powers of Organ- 

 isms to extend their Areas of Dispersal — This Dispersal 

 not Fortuitous but governed by Law ... ... ... 285 



LIST OF MAPS. 



1. Map showing the loo-Fathom and 50-Fatiioni 



Contours of the British Area ... ... ... 'Jo face page 5 



II. Map sliowing the 40-Fathom, 20- Fathom, and 



15-Fathom Contours of the British Area ... ,, ,, 21 



III. Map showing Range Base or Refuge Area L ... ,, ,, 47 



IV. Map showing Range Base or Refuge Area II. ... ,, ,, 71 

 V. Map .showing Range Base or Refuge Area III. ... ,. ,, 95 



VI. Chart .showing the Principal Migration Routes 



into the British Area ... ... ... ... ,, ,, 209 



