i8 INTRODUCTION. 



carries off the weak and unfit, and that 

 the death-rate is not affected to a very 

 great extent? And is it not also true 

 that the elimination is a part of the great 

 scheme ? 



Under the law of self-defence man has a 

 right to destroy his enemies, but as a reason- 

 able being he must first be sure that what he 

 is trying to exterminate is entirely noxious. 

 From the study of nature in its various aspects 

 I have come to the conclusion that there is 

 no such thing as an unmitigated pest. It 

 all depends on the standpoint ; on the one 

 hand a species may be a pest or at least 

 a nuisance, on the other it is a pest de- 

 stroyer. When left alone the balance is 

 ultimately adjusted. Meanwhile we must 

 see what can be done. 



Plagues and famines come within the pro- 

 vince of the student of nature ; they are checks 

 on abnormal increase. Being part of the 

 great scheme, we must not hastily stigmatise 



