146 THE COLOUES OF ANIMALS 



mined during the time when the caterpillar was 

 motionless in the box. 



Still later in 1888 Dr. E. G. Lynam sent me some 

 cocoons of the Gold-tail Moth (Liparis auriflua) which 

 had been also modified in a similar manner, and I 

 found that the same power is possessed by the cater- 

 pillar of the Brimstone Moth (Rumia crat&gatd) . l In 

 this latter case a green tissue-paper background pro- 

 duced brown cocoons like those spun upon green leaves. 



It is probable that this power of adjusting the 

 colour of the cocoon is very common among species 

 which spin in exposed situations. It may also be 

 expected to occur in those Hymenoptera with similar 

 habits. The investigation of the physiological pro- 

 cesses involved in the adjustment would be of extreme 

 interest. Last year (1888) I obtained a large number 

 of Small Eggar caterpillars, intending to begin such 

 an investigation, but nearly all of them died just 

 before reaching maturity. It is to be hoped that 

 many species will now be tested in order to ascertain 

 whether this form of susceptibility is present. 



Variable Protective Resemblance in Lepidopterous 

 larvae 



It now remains to briefly consider the power of 

 colour-adjustment possessed by certain caterpillars. 

 Naturalists have long known that in certain species 

 1 Proc. Ent. Soc. Land. 1888, p. xxviii. 



