igo THE BOOK OF NATURE STUDY 



that is not fully understood. The eyes are not the percipient 

 organs in this matter. 



During the pupal stage extensive rearrangements of the 

 internal organs take place, and some of the tissues break down 

 into a pulpy mass from which are elaborated the new muscles 

 and other organs peculiar to the imago. In other words, a large 

 series of changes have been compressed into the brief compass 

 of the pupal life, so that now the modifications necessary to 

 convert a biting and crawling larva into a sucking and flying 

 imago are accomplished during the one long period of repose. 

 The autumn-formed pupae pass through the winter in that con- 

 dition. When the imago is ready to emerge the colour of the 

 pupa changes a little ; eventually the skin of the anterior region 

 breaks open and the butterfly crawls out, wet and limp and 

 with small crumpled wings that are full of fluid. Drops of a 

 pinkish fluid are usually discharged from the posterior end soon 

 after emergence. These contain the nitrogenous waste matter 

 which has been formed and accumulated during the important 

 tissue changes of the pupal period. The wings soon lengthen 

 out, hanging down with their edges parallel with the abdomen. 

 After a few hours they dry, the liquid within disappearing, and 

 soon after this has taken place the butterfly flits away. 



BIBLIOGRAPHY. Miall, Round the Year ; Meyrick, Handbook of British Lepid- 

 optera ; Poulton, Trans. Entom. Soc., London, 1892 ; Poulton, The Colours of 

 Animals ; Cambridge Natural History, vol. vi. 



