vi PREFACE 



history of strife with the elements, of invasions, of 

 colonization, of the formation of communities and asso- 

 ciations. In the course of time they change ; some perish ; 

 others give origin to new forms destined one day to dis- 

 place them, and, through their superior qualities, to win 

 a habitation which they themselves could not retain. 



The book is divided into three parts. The first part 

 deals with fundamental ecological considerations the 

 factors of the environment water, temperature, light, 

 air, and soil. 



The second part comprises a general description of 

 British plants examined in the light of these factors and 

 considered as an outcome and expression of them. 



The third part is an attempt to present in an elementary 

 manner the physiognomy of the British flora in its most 

 conspicuous associations, to explain its origin and develop- 

 ment, and to analyze its present distribution. 



The matter dealt with in the third part covers a wide 

 field, and in the present state of our knowledge only a 

 broad survey can be attempted. This department of the 

 science is quite a recent one, but the principles of eco- 

 logical botany are now fairly well known. It only remains 

 for the student to apply them to the interpretation of the 

 facts of the flora of his own neighbourhood. 



The book is designed as a companion to the elementary 

 text-book and the field flora. Most examination-papers 

 now contain questions on ecology, but they are seldom 

 attempted with success. Special attention has been 

 given to the claims of the general reader as well as to 

 the needs of students and teachers of Nature Study. 

 The subject-matter, therefore, has been treated wherever 

 possible in a suggestive manner, so that interest may be 

 awakened and inquiry stimulated. With this end in 

 view, we have been sparing of technical terms, and care 

 has been taken to explain their meaning and to give their 

 derivation where necessity or convenience has compelled 

 their use. 



