94 



INSECT TRANSFORMATION 



like the dragon-fly grub, to depend on dissolved air for its 

 supply of oxygen. The newly-hatched insect (Fig. 52 A) has 

 no special breathing organs, the necessary gaseous exchange 



B 



FIG. 52. MAYFLY LARVAE AND NYMPHS (Heptdgenia) . 



A, Third instar. X 16. a, abdominal appendage ; a^, abdominal appendage 

 of instar. x 45. B, Front region of seventh instar with small wing-rudiments 

 (w). x 12. b, an abdominal appendage, x 45. C, Eighth instar with prominent 

 wing-rudiments (legs are shown on right, abdominal gill-appendages on left). 

 X 4. c, a gill-appendage, x 15. After Vayssie're, A nn. Sci. Nat. Zool. XIII. 



being carried on through the delicate cuticle. In the genus 

 Cloeon there are over twenty moults during the life-history. 1 

 In the third instar seven pairs of appendages are evident 



1 J. Lubbock : " The Development of Chloeon ". Trans. Linn. Soc., 

 Land., XXIII. 1863. 



