80 THE THEORIES OF EVOLUTION 



Darwin's own point of view, contending that all spe- 

 ^ cific characters serve some useful purpose and that it is 

 only our ignorance as to the life and habits of animals 

 which prevents us from discovering that purpose. It 

 must be said that researches in this direction have re- 

 vealed many uses which were not apparent at first 

 glance. Still we must beware of the influence that 

 preconceived ideas may have upon such observations 

 and avoid the anthropomorphic construction which we 

 might be tempted to place upon all natural phenom- 

 ena. 



Weismann endeavours, for instance, to demon- 

 strate that not only a colouring similar to that of the 

 environment (white fauna of polar regions, trans- 

 parent aquatic specimens, green-coloured animals 

 living in the grass or on the leaves, etc. ) , but also the 

 varied markings on the wings of butterflies, have their 

 usefulness, as they tend to protect the animal by mak- 

 \ ing it unnoticeable or by causing a species to look like 

 another better-protected species (mimicry) or to 

 frighten away its foes. 



"Among Lepidoptera, too, eye-spots often occur 

 on the wings, and to some extent, at least, they have in 

 this case also the significance of warning marks. 

 Take, for instance, the large blue and black eye-spots 

 on the posterior wings of the e yed hawk-mot h (Smer- 

 inthus ocellatus) . When the insect is sitting quietly 

 the two spots are not visible, as they are covered by 



