198 THE COLOURATION OF INSECTS 



like fungus spots. Near the tip was an absolutely pure 

 white marking, shining, which probably represented a 

 silvery patch such as is often seen on a dried leaf. The 

 most realistic portion of the resemblance was the deception 

 produced by the very dark brown of the anterior surface of 

 the head, which appeared to be the dark shadow of the 

 interior of the tube formed by the supposed dead and 

 rolled-up dry leaf. 



The completeness of the likeness cannot be realized 

 when the moth is seen set in the cabinet, but it was one 

 of the most perfect examples of special procrypsis that I 

 have ever seen. 



Precisely the same attitude is made use of by the " Bufif- 

 tip moth," but in this case the colouring causes it to 

 resemble a short piece of very dry stick with light grey 

 bark, broken o£E square at one end and obliquely at the 

 other. In the case of this moth there is again to be noted 

 the profound change necessary for the complete success 

 of the deceptive resemblance. The deeply rooted instinct 

 to escape when alarmed has been modified into a stronger 

 instinct to remain motionless at all costs in order to 

 maintain the appearance of a dead leaf, for the slightest 

 movement would attract the eye of an enemy, who would 

 certainly investigate the object more closely and perhaps 

 handle it roughly. The Mutationist who believes that this 

 deceptive appearance, so minutely perfect, was produced 

 more or less complete in one step, will have to admit 

 that the sudden modification of instinct, by a strange 

 coincidence, took place at the same time, or that at least 

 it occurred in connection with the other. The Darwinian, 

 on the other hand, believes that both modifications took 

 place by equally slow gradations. 



Very interesting examples of special procryptic colour- 

 ation are the resemblances of insects to bird droppings 

 on leaves. There is a beautiful example in England — 

 the little moth Cilix glaucata at rest fully exposed on a 



