The Origin of the Markings of Caterpillars. 387 



show the same markings in allied (younger?) 

 species, both in a rudimentary and in a transformed 

 condition. These markings may thus contribute 

 to the formation of a latticed or reticulated pattern. 

 Even the oldest marking, the subdorsal line, may 

 still play a part, since its remnants cause certain 

 portions of the complicated pattern to appear more 

 strongly marked (S. Convolvuli). Finally, when 

 an adaptation to a changing environment in- 

 tersected by lights and shadows is required, new 

 markings may be here added as in other cases, 

 viz., dark streaks extending over the light surface 

 of the whole caterpillar. 



In concluding this essay, I may remark that, 

 with respect to the wide and generally important 

 question which gave rise to these investigations, 

 a clearer and simpler result has been obtained than 

 could have been expected, considering the com- 

 plexity of the characters requiring to be traced 

 to their causes, as well as our still highly imperfect 

 knowledge of ontogenetic and biological facts. 



For a long time I believed that it was not 

 possible to trace all the forms of marking and their 

 combinations to those causes which are known to 

 produce transformation ; I expected that there 

 would be an inexplicable residue. 



But this is not the case. Although it cannot 

 yet be stated at first sight with certainty in every 

 single instance how far any particular element of 

 marking may have a biological value in the species 



c c 2 



