8 



pillars can stand the influence of alcohol. I therefore had to conHno 

 myself to the arrangement of the setae. For the solution of the 

 third question I could only collect a few data which will be 

 mentioned under the species of which I have exaniined the pupae. 

 In chapter VII I intend to come back to this point. As only tlioso 

 naturalists, who have a very extensive collection at their disposal 

 can fully solve this problem, I am obliged to leave the further 

 investigation to others. 



In working out the different questions I became convinced that 

 the 4''» and the 5»l> are the cardinal points of the investigation. 

 Through the 4^^ question especially I came into contact with pro- 

 blems, which entirely differed from those I had originally thought 

 of. Here too I wish to thank Prof. J. F. vax Bemmelen for the 

 manner in which he encouraged me to enlarge the subject of my 

 investigations, and for the way in which he inspired me with 

 interest for it and also for his kindness in assisting mo with his 

 knowledge of the extensive literature. 



§ 2. Material and Method. 



There are a great number of books about caterpillars, with 

 coloured and uncoloured figures, but most of them are unsuitable 

 for my purpose. In general the figures of caterpillars are still 

 more inaccurate than those of their imagines, of which van 

 Bemmelen said (1913, p. 107), that he found one great difficulty 

 in his work on the colourpattern of the body of Lepidoptera', viz: 

 that neither most of the existing figures of butterflies and moths, 

 nor the dried specimens of the collections were suitable for a 

 more exact analysis of this part of their colour-pattern, and that 

 this was the same with the very few figures of the nymphs and 

 caterpillars in the entomological illustrated publications. I cannot 

 but agree with these words, making an exception for Packard's 

 standard-work on the Bombyces (1895 — 1914). As it would be 

 too expensive to make such large photographs of each caterpillar 

 as VAN Bemmelen did for the nymphs of Papilio machaon and 

 podalirius, Vanessa to, Pieris brassicae and napi, Aporia crataegi^ 



