The Making of Species 



themselves, but rest on the upper surfaces of 

 leaves and flowers. Moreover, they all have 

 juices which exhale a powerful scent ; so that, if 

 they are killed by pinching the body, a liquid 

 exudes which stains the fingers yellow, and leaves 

 an odour which can only be removed by re- 

 peated washing. This odour is not very offen- 

 sive to man, but has been shown by experi- 

 ment to be so to birds and other insect-eating 

 animals. 



" Warning colours are advertisements, often 

 highly coloured advertisements, of unsuitability 

 as food. Insects are of two kinds those which 

 are extremely difficult to find, and those which 

 are rendered prominent through startling colours 

 and conspicuous attitudes. Warning colours 

 may usually be distinguished by being con- 

 spicuously exposed when the animal is at rest. 

 Crude patterns and startling contrasts in colour 

 are characteristically warning, and these colours 

 and patterns often resemble each other; black 

 combined with white, yellow, or red, are the 

 commonest combinations, and the patterns usually 

 consist of rings, stripes, or spots." 



We trust that we shall be forgiven for this 

 lengthy quotation. Our object in reproducing so 

 large an extract is to allow the Neo- Darwinians 

 to speak for themselves. Were we to state their 

 theory in our own words, we might perhaps be 

 charged with stating it inaccurately. We should 



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