56 The Study of Animal Life parti 



Perhaps the best illustration which Belt gives is that of 

 a certain gaily-coloured frog : — 



" In the woods around Santo Domingo there are many frogs. 

 Some are green or brown, and imitate green or dead leaves, and 

 live amongst foliage. Others are dull earth-coloured, and hide in 

 holes and under logs. All these come out only at night to feed, and 

 they are all preyed upon by snakes and birds. In contrast to these 

 obscurely-coloured species, another little frog hops about in the 

 daytime dressed in a bright livery of red and blue. He cannot be 

 mistaken for any other, and his flaming vest and blue stockings 

 show that he does not court concealment. He is very abundant 

 in the damp wood, and I was convinced that he was uneatable 

 so soon as I had made his acquaintance, and saw the happy sense 

 of security with which he hopped about. I took a few specimens 

 home with me, and tried my fowls and ducks with them, but none 

 of them would touch them. At last, by throwing down pieces of 

 meat, for which there was a great competition amongst them, I 

 managed to entice a young duck into snatching up one of the 

 little frogs. Instead of swallowing it, however, it instantly threw 

 it out of its mouth, and went about jerking its head, as if trying to 

 throw off some unpleasant taste." 



Admirable, also, are the illustrations given by Mr. Poulton 

 in regard to many caterpillars, such as the larva of the 

 currant or magpie moth {Abraxas grossulariatd), which is 

 conspicuous with orange and black markings on a cream 

 ground, and is refused altogether, or rejected with disgust, 

 by the hungry enemies of other caterpillars. Professor 

 Herdman and Mr. Garstang have also shown that the 

 Eolid Nudibranchs (naked sea-slugs), with brightly-coloured 

 and stinging dorsal papillae, are rarely eaten by fishes ; and 

 the same is true of some other conspicuous and unpalat- 

 able marine animals. 



The general conclusion seems fairly certain that the 

 conspicuousness of many unpalatable or noxious animals is 

 imprinted on the memory of their enemies, who, after pay- 

 ing some premiums to experience, learn to leave animals 

 with " warning colours " alone. It will be interesting 

 to discover how far the bright colour, the nauseous taste, 

 the poisonous properties, the distasteful odour, sometimes 

 found associated, are physiologically related to one another, 

 but to answer these questions we are still unprepared. 



