The Origin of the Markings of Caterpillars. 281 



the last stage of the ontogeny, may also be de- 

 monstrated from the markings of caterpillars. It 

 is, of course, not hereby implied, that throughout 

 the whole animal kingdom new characters can 

 only appear in the last ontogenetic stage. Haeckel 

 is quite correct in maintaining that the power of 

 adaptation of an organism. is not restricted to any 

 particular period. Under certain circumstances 

 transformations may occur at any period of de- 

 velopment ; and it is precisely insects undergoing 

 metamorphosis that prove this point, since their 

 larvae differ so widely from their imagines that 

 the earlier stages may be completely disguised. 

 It is here only signified that, with respect to the 

 development of caterpillars, new characters first 

 appear in the adult. The complexity of the mark- 

 ings, which so frequently increases with the age 

 of the caterpillar, can scarcely bear any other 

 interpretation than that the new characters were 

 always acquired in the last stage of the ontogeny. 

 In certain cases we are able, although with some 

 uncertainty, to catch Nature in the act of adding 

 a new character. 



I am disposed to regard the blood-red or rust- 

 red spots which occur in the last stage of the three 

 species of Smerinthus larvae in the neighbourhood 

 of the oblique stripes as a case in point. It has 

 already been shown that these red spots must be 

 regarded as the first rudiments of the linear coloured 

 edges which reach complete development in the 



