The Origin of the Markings of Caterpillars. 369 



tations first, in species sought by enemies, on an 

 adaptation to the colour of the soil ; and secondly, 

 in species rejected by foes, on the endeavour to 

 produce the greatest possible contrast of colour. 



Moreover, the supposition from which this last 

 plea for a vital force set out is not universally 

 correct, since there are species, such for instance 

 as D. Niccea, which never acquire a dark colour ; 

 and in D. Galii also, although all the individuals 

 abandon the protective green of the young stages, 

 they by no means all acquire a dark hue in ex- 

 change for this colour ; many individuals in their 

 light ochreous-yellow colouring rather strikingly 

 resemble the snake-like caterpillar of D. Niccza. 



B b 



