INSECT TRANSFORMATION 



regions of its body out of the water breathes atmospheric air 

 through the now open thoracic spiracles. Beneath the old 

 cuticle, the new imaginal cuticle is formed, causing some 

 striking changes in appearance and colour. At length the 

 nymph crawls up some water-plant ; the internal growth goes 



D. 



F 



G. 



FIG. 27. 



A F, Forms of rectal gills of dragon-fly larvae, x 10. A, Austrogomphus (undulate type); 

 B, Austroaeschna (implicate type) ; C, Aeschna (foliate type) ; D, Anax (papillo-foliate) ; 

 F,, Synthemis; and F, Diplacbdes (lamellate); G, H, Caudal gills (modified cerci) of Damsel-fly 

 larvae, x 12. G, Ischnura; H, Agriocnemis, showing air-trunks with branching tracheoles. 

 From Tillyard, " Biology of Dragon-flies ". 



on so rapidly that the cuticle of the nymphal thorax splits 

 along the mid-dorsal line, and the fly withdraws first the thorax, 

 then the head and legs, and then the front abdominal region, 

 hanging head downwards (Fig. 28 a) until the cuticle of the 



