240 NOVEMBER 



draws its head into the first body ring, and presents 

 to the astonished observer a large flat face, which 

 is a greatly exaggerated caricature of a vertebrate 

 countenance. This caterpillar is so alarming in 

 appearance that a certain learned entomologist who 

 saw it for the first time was afraid to touch it when 

 it assumed its terrifying attitude, and appeared to 

 glare at him with its two eye-marks, resembling jet- 

 black eyes. 



When we thus see how cleverly an insect can 

 protect itself against its natural foes by assuming 

 warning forms and colours, it at once strikes the 

 careless observer that the remarkable thing is that 

 more species have not availed themselves of the 

 process. We see about us on a summer walk two 

 great groups of insects those which so closely 

 resemble surrounding objects that they are almost 

 indistinguishable from them, and those which are 

 so brilliantly coloured that they must attract atten- 

 tion from every living creature. We are quick to 

 conclude that the brightly coloured ones are pro- 

 tected by flavour or texture from death by hungry 

 enemies ; and it seems absurd that the other duller 

 creatures, which are only protected by a certain 

 resemblance to their surroundings, should not have 

 adopted a more aggressive means of self-preserva- 

 tion. There must be some principle antagonistic 

 to such a mode of protection, and this principle 

 would be found in the too complete success of the 

 method. If a very common insect which formed 

 the staple food of some animal took such a means 

 to protect itself, the predatory animal would be 

 forced to eat unpalatable food to avoid starvation. 



