326 Darwin, and after Darwin. 



tective Resemblance, and one may search a long time before 

 finding it, although assured of its presence from the stripped 

 branches of the food-plant and the faeces on the ground beneath. 

 As soon as a large larva is discovered and disturbed it with- 

 draws its head into the first body-ring, inflating the margin, 

 which is of a bright red colour. There are two intensely black 

 spots on this margin in the 

 appropriate position for eyes, 

 and the whole appearance is 

 that of a large flat face ex- 

 tending to the outer edge of 

 the red margin (see Fig. 112). 

 The effect is an intensely ex- 

 aggerated caricature of a ver- 

 tebrate face, which is probably 

 alarming to the vertebrate 

 FIG. ii2.-The larva of Puss Moth enemies of the caterpillar. The 

 '-ifying effect is therefore 

 mimetic. The movements en- 

 tirely depend on tactile im- 

 pressions : when touched ever so lightly a healthy larva im- 

 mediately assumes the terrifying attitude, and turns so as to 

 present its full face towards the enemy ; if touched on the 

 other side or on the back it instantly turns its face in the ap- 

 propriate direction. The effect is also greatly strengthened by 

 two pink whips which are swiftly protruded from the prongs 

 of the fork in which the body terminates. The prongs represent 

 the last pair of larval legs which have been greatly modified 

 from their ordinary shape and use. The end of the body is at 

 the same time curved forward over the back (generally much 

 further than in Fig. 1 12), so that the pink filaments are brandished 

 above the head. 



Mimicry. 



Lastly, these facts as to imitative and conspicuous 

 colouring lead on to the yet more remarkable facts of 

 what is called mimicry. By mimicry is meant the 

 imitation in form and colour of one species by another, 



