38 THE BOOK OF THE FLY 



their destined shape, the immensely increased head 

 and the thorax with its appendage members slowly 

 emerge, and the partly inverted integument of the 

 abdomen rolls back, disclosing the shape of a fly not 

 before recognisable. 



Other naturalists would have it believed that the 

 true account of the transformation is as follows, when 

 the maggot has shrunk and freed its body inside its 

 skin which forms the case or puparium, all its pre- 

 existing internal organs become absolutely dissolved ; 

 then out of the fluid mass a new growth ensues, con- 

 stituting the pupa with its recognised shape. This 

 account is the one represented in most modern 

 entomological books, and is based partly upon B. T. 

 Lowne's monographic work on the blow-fly. 



The comparative embryologist of our day is inclined 

 to be a hyper-theorist, and so it seems that some have 

 not remained content with either of the above accounts ; 

 to them, apparently, the production of the large and 

 complex head of the imago out of a single small 

 anterior segment of the maggot requires a more recon- 

 dite explanation, and must be brought into harmony 

 with analogous facts. To this end some degree of 

 linked support is found by the investigations of micro- 

 scopic anatomy, and it has been conjectured that not 

 one or two head segments, but five are lying blended 

 and embryonically hidden in the larvae, all ready to 

 bud forth. However, for fear of wearying too much 

 with the theories of advanced erudite scientists, the 

 following jeu d 'esprit is presented, instead of a more 

 elaborate and sober attempt, to lure the unscientific 

 lay reader to an extreme hypothetical conception of 



