THE DRAMA OF LIFE 33 



with a bad reputation that it has come to associate with. 

 In all such cases single observations are unconvincing, but 

 when similar cases accumulate the argument gathers force. 

 Thus it is very interesting that J. Bourgeois should have 

 noticed Ceria conopsoides visiting the wounds on the trunk 

 of a horse-chestnut in company with a wasp, Odynerus 

 crassicornis, a formidable insect. Both were visiting the 

 tree with the same end to lick the exudation ; the fly 

 was probably protected from certain enemies by its ' Bate- 

 sian mimicry ' of the wasp. 



Another type of mimicry is called Miillerian, after the 

 naturalist Fritz Miiller, and here we have a resemblance 

 between several immune species living in the same country. 

 This is well illustrated among South American Lepidoptera, 

 e.g. Danaids, Heliconids, and Acraeids, and it seems to 

 work like a sort of mutual assurance. None are palatable, 

 but by being like one another they spread the risk of being 

 experimented on by inexperienced birds. Birds have to 

 learn discretion in their youth ; they take many an unpleas- 

 ant bite of unpalatable victims before they become pro- 

 ficient ; they remember the marks of bad taste, and the 

 more similar these marks are the more likely their possessors 

 are to escape. The more in the ring, the less the waste of life. 



There are many difficulties in connexion with mimicry 

 especially perhaps the question of its evolution but it is 

 difficult to see the remarkable illustrations collected by 

 Professor Poulton and to consider the facts he adduces 

 as to its efficacy in certain cases, without being ready to 

 admit that it plays a considerable and curious part in the 

 drama of animal life. 



Sometimes the mimicry is very exact as regards colouring 

 and pattern ; sometimes it is rather in pose and movement, 



D 



