38 INSECT TRANSFORMATION 



the newly-revealed imago rests with its head above, its 

 abdomen and wings hanging downwards, while the cuticle 

 undergoes the final stretching and hardening processes 

 (Fig. 20 c). 



The changes connected with the wings are of especial 

 interest. The cuticle which covers these organs has been 

 formed within the wing-rudiments of the preceding instar 

 previously to the moult, and as these rudiments extend only 

 to about a third of the length of the abdomen, the enclosed 

 wings must necessarily be crumpled and folded. When first 

 withdrawn from the old cuticle, they are straight and parallel 

 to the abdomen, but as the imago hangs head downwards, 

 and the blood and air pass into the wings so that they begin 

 to expand and stiffen, this operation progressing from the 

 bases onwards, their tips bend down so that they assume a 

 procurved position over the thorax (Fig. 20 b). Then, as by 

 the bending of the abdomen (Fig. 20 c), the head of the insect 

 becomes directed upwards and the abdomen points downwards, 

 the wings, continuing to expand, assume again the normal 

 position parallel to the abdomen which they exceed in length 

 when they have attained their full size. It is noteworthy 

 that at first the costa of the wings is directed dorsalwards, 

 and that the broad hindwings, as yet unfolded, lie external to 

 the narrower and longer forewings. But, as the wing-cuticle 

 attains its ultimate firm and hard texture, these positions 

 become reversed ; through a basal torsion, the wings of both 

 pairs come to have the costa directed ventralwards, and 

 the hindwings, their delicate areas folded fanwise, are brought 

 to a position between the forewings which serve to cover and 

 protect them (Figs. I B igf). 



Briefly surveying the course of the grasshopper's life-history, 

 we note that the newly-hatched insect closely resembles its 

 parents, that through its subsequent development it lives and 

 feeds in much the same way, being active in every period of 

 its growth, and that the wing-rudiments appear outwardly 

 at an early stage and increase in size after each moult, with 

 somewhat sudden advances however in the fourth and final 

 instars. These facts will be found of importance for com- 

 parison with those displayed in the life-histories of other insects. 



