VI] ''MIMICRY RINGS" 71 



been brought about by a succession of slight vari- 

 ations must also assume that model and mimic were 

 closely alike to start with, and this certainly cannot 

 be true in many cases. On the other hand, there is 

 so far no reason against the idea of supposing the 

 resemblance to have originated suddenly except what 

 to most minds will probably appear its inherent im- 

 probability. 



There are writers on these questions of mimicry 

 who adopt a view more or less intermediate between 

 those just discussed. They regard the resemblance as 

 having arisen in the first place as a sport of some 

 magnitude on the part of the mimic, rendering it 

 sufficiently like the model to cause some confusion 

 between the two. A rough-hewn resemblance is first 

 brought about by a process of mutation. Natural 

 selection is in this way given something to work on, 

 and forthwith proceeds to polish up the resemblance 

 until it becomes exceedingly close. Natural selection 

 does not originate the likeness, but, as soon as a rough 

 one has made its appearance, it comes into operation 

 and works it up through intermediate stages into the 

 finished portrait. It still plays some part in the 

 formation of a mimetic resemblance though its role is 

 now restricted to the putting on of the finishing touches. 

 Those who take this view hold also that the continued 

 action of natural selection is necessary in order to keep 

 the likeness up to the mark. They suppose that if 

 selection ceases the likeness gradually deteriorates 

 owing to the coming into operation of a mysterious 



