The Origin of the Markings of Caterpillars. 367 



ment, which alone invests the caterpillar with a sin- 

 gular, and, to smaller foes, an alarming appearance. 

 We know that in the case of those Ch&rocampa- 

 larvse which possess no eye-spots, the distension of 

 this segment is employed against hostile attacks. 

 (See the illustration of Darapsa Chcerilus, PL IV., 

 Fig. 34.) Those markings which even only re- 

 motely resembled an eye must, in such a posi- 

 tion, have increased the terrifying action. On 

 these grounds I believe that it may be safely 

 admitted, that this kind of marking possessed the 

 same significance in its initial stages as it now 

 does when fully perfected. No functional change 

 has here taken place. 



Among all the facts brought together in the 

 first section I only know of one group of 

 phenomena which at least permit of an attempt to 

 refer them to a phyletic vital force. This is the 

 occurrence of dark ground-colours in adult larvae 

 which are of light colours in their young condi- 

 tion. I have already attempted to show that in the 

 Chcerocampa-\dxv&, this change of colour depends 

 on a double adaptation, the young caterpillars 

 being adapted to the green colour of the plant 

 and the adults to the soil and dead leaves. This 

 interpretation appears the more correct when we 

 find the same process, viz. the gradual replacement 

 of the original green by brown colours, among 

 species of widely different genera, which, with 

 the dark colouring, possess the necessarily 



