BRITISH BLOODSUCKERS 257 



same scale as the insect itself, you would fail to 

 perceive them. 



Is it not marvellous, too, that the same set of 

 organs about the mouth, which we saw employed 

 by the wasp for cutting paper from wood, and 

 by the ant for the varied functions of civilised 

 ant-life, should be capable of modification in the 

 butterfly into a sucker for honey, and in the gad- 

 fly into a cunning mechanism for piercing thick 

 hides and feeding on the life-blood of superior 

 animals. Nature, it seems, is sparing of ground- 

 plan, but strangely lavish of minor modifications. 

 She will take a single set of organs, inherited from 

 some early common ancestor, and keep them true 

 in the main through infinite varieties ; but as 

 habits alter in one species or another, she will 

 adapt one of these sets to one piece of work 

 and another to a second wholly unlike it. While 

 she preserves throughout the similarity due to a 

 common origin, she will vary infinitely the details 

 and the minor structures so as to make them 

 apply to the most diverse functions. Nothing 

 shows this truth more beautifully, and more 

 variously, than the mouths of insects ; and though 

 the names by which we call the different parts 

 are, I will admit, somewhat harsh and technical, 

 I feel sure that anybody who once masters their 

 meaning cannot fail to be delighted by the end- 

 less modifications by which a few small instru- 

 ments are made to fit an ever-increasing and 

 infinite diversity of circumstances. 



