THE HIDDEN TYPE OF WING-GROWTH 153 



another (Fig. 86 B C). In those larvae which possess thoracic 

 legs such as the grubs of many beetles or the caterpillars 

 of moths the outpushed legs of the pupa may lie partly 

 within the corresponding larval legs during the final larval 

 stage. It was long ago noticed that if one leg of a fully-grown 

 caterpillar were cut off the resulting butterfly emerged with 

 a mutilated foot, the terminal portion of the relatively long, 

 segmented leg of the pupa projecting into the short limb of 

 the final larval instar. In larvae that differ most profoundly 



FIG. 87. PUPAL WINGS OF MOTH 



Showing tracheal tubes prefiguring nervures. Lettering as in 

 Fig. 35. x 2. After Tillyard, Proc. Linn. Soc. N.S. Wales, 

 XLIV. 



from the perfect insect, such as the maggots of house-flies 

 and blue-bottles, the imaginal leg-buds (Fig. 86 A) grow far 

 into the interior of the body, each retaining its connexion with 

 the outer body-wall only by a slender stalk or chain of cells. 

 Finally we pass to the origin of the wings themselves. 1 

 It has been already mentioned (ch. ii, pp. 63-4, Fig. 34) that 

 a wing-bud appears as a small pad growing into a pouch 



1 J. Gonin : " Recherches sur la Metamorphose des Lepidopteres ". 

 Bull. Soc. Vaud. Sci. Nat. XXXI. 1894. W. F. Mercer : " The Develop- 

 ment of the wings in Lepidoptera ". Journ. New York. Entom. Soc., VIII. 

 1900. 



