212 HUXLLV AND NATURAL SELECTION 



recognized that the resemblance between his mimic and 

 his model was a very poor thing as compared with the 

 astonishinir likeness of one model to another. And there 

 is no question of affinity in the resemblance of models any 

 more than in that of mimic and model. In i^^79, when 

 Tritz Miillcr offered an explanation of these m)stcrious 

 resemblances,' the Ixitcsian theory had been before the 

 world for seventeen years, and had attracted a great deal 

 of attention, burthermore, the examples selected by 

 Aliiller were not very striking, and were illustrated 

 without the use of colour. He made the illuminating 

 suggestion that the resemblance between the dominant 

 models was mutually advantageous, inasmuch as it facili- 

 tated the education of their inexperienced foes, reducing 

 the amount of destruction which must be wrought during 

 the time in which }oung birds and other insect-eating 

 animals are learning what to eat and what to avoid. If 

 .'1 and /j be two distasteful species closely resembling- 

 each other, and if they be equally common, an individual 

 of j^l will be seized before B by an inexperienced enemy 

 as often as an individual of B before A. In the first 

 case B benefits from the unpleasant effects produced by 

 A, in the second A benefits from the effects of B. 

 Professor Llo)d Morgan's observations upon the activities 

 and instincts of young birds of many species^ prove that 

 their education is actually of the kind presupposed by the 

 MuUerian theory. He shows that they have no instinctive 

 knowledge of things which are good for food, but examine 

 and test ever)thing. On the other hand, they have very 

 good memories, and retain a firm imi)ression of the appear- 

 ance of objects whicli have given them an unpleasant 

 experience, b^irthermore, there is evidence that they 

 are infiucnced in their behaviour towards objects resem- 

 bling the one which has proved objectionable to them. 



Fritz Muller's paper was translated by Professor R. Mel- 

 dola,and published in this countr)almost immediately after 

 its appearance, ■ with the result that the theory has been 



' In Knsrnns, for May, 1879, I** '°o- 

 * Habit and Insiinit, London, 1896. 

 ^ Proc. Ent, Soc, Lond.y 1879, p. xx. 



