VAEIABLE PROTECTIVE RESEMBLANCE IN INSECTS 113 



The History of the Discovery of Variable Protective 

 Resemblance in the pupae of Butterflies 



In 1867 Mr. T. W. Wood exhibited to the Entomo- 

 logical Society of London ^ a number of chrysalides of 

 the Swallow-tailed Butterfly {Papilio machaon), and of 

 the large and small Garden White Butterflies (Pieris 

 hrassicce and P. rapce), which corresponded in colour to 

 the surfaces to which they were attached. Dark 

 pupae had been found on tarred fences and in subdued 

 light ; light ones on light surfaces ; while green leaves 

 were shown to produce green chrysalides, at any rate 

 in certain cases. Mr. Wood's inclusion of the chrysalis 

 of the Swallow-tail, with which he states that he was 

 imperfectly acquainted, was most unfortunate, and 

 doubtless prevented his suggestive paper from gaining 

 the success it deserved. It is quite true that this 

 chrysahs appears in two forms, being sometimes green 

 and sometimes dark grey ; but, without sufficient evi- 

 dence, it was unwise, although most natural, to assume 

 that these colours could be adjusted to green or dark 

 surroundings respectively. I have since tested the 

 chrysalis, and as far as my experiments (which were 

 with small numbers) are conclusive, they show that it 

 has no power of adjustment.'^ In the discussion which 

 followed Mr. Wood's paper, Mr. Bond stated that * he 



» Proc. Ent. Soc. 1867, pp. xcix.-ci. 



2 Phil Trans vol. 178 (1887), B. p. 406-408. 



