136 THE DARWINIAN THEORY 



extremely conspicuous, is either refused altogether 

 by birds, lizards, frogs, and spiders, or else causes 

 them to exhibit signs of most intense disgust 

 after eating it. The caterpillars of the Tiger-moth, 

 the Burnet, and the Buff-tip are all brightly coloured 

 and nauseous. 



It has been objected, first, that the protection 

 afforded by warning colours is only imperfect, that it 

 must not be overdone, and is only available to a few ; 

 that the likes and dislikes of insect-eating animals 

 are purely relative, and hunger will drive them to 

 extremes and overcome taste, hence giving rise to 

 contradictory results of experiments. But this is the 

 very essence of natural selection, which preserves 

 advantageous characters, but does not lead to per- 

 fection. Secondly, it has been stated that " tasting 

 is quite as dangerous to the caterpillar as swallowing 

 outright," and hence it is argued that there is no 

 advantage. But this, again, is a misconception, for 

 although the individual may suffer, the species will 

 benefit through the lesson learnt by its death. 



Eisigs theory of warning colours states that the 

 pigment itself is the cause of the distastefulness, and 

 that it is very probably excretory in nature. 

 According to this, the brilliant colours — ie., the 

 abundant secretion of pigment — have caused the in- 

 edibility of the species, rather than that the inedibility 

 has necessitated the production of bright colours as 

 an advertisement. Brilliant colouring is the normal 

 condition in caterpillars, and the advent of birds led 

 to protective modifications, except when combined 

 with inedibility. 



