92 The Life-History of Insects 



of the primitive streak into the egg 



Fig-. 6o. — A. B. C. Developing egg of (Grasshopper 

 (Xiphidiuiii). evi. embryo; in. indusium ; in'. 

 furthest extension of indusium. D. Young embryo 

 Qi{Xiphidiu7n, ind. indusium. E. Embryo of Spring- 

 tail (.^«;(r/^a). «//. micropyle (probably a vestigial 

 indusium); p.cl. procephalic lobes; tii. mouth; /. 

 labrum; ««/. antennas; /c. tritocerebral appendage ; 

 7np. mandibles; nix^. m.x-. ma.\ill2e i and 2; pt., 

 mst., 7i!tt. thoracic segments; an. anus. From 

 Carpenter (after Wheeler), Natural Science, vol. 3. 



amnion. This is the inditshim (fig 60 



, the necessarily 

 simultaneous 

 inpushing of 

 the adjoining 

 blastoderm 

 forming the 

 amnion (53). 

 The developing 

 embryo is thus 

 transferred to 

 the dorsal face 

 of the egg (fig. 

 60 A, B) while 

 the edges of 

 the blastoderm 

 reunite around 

 the invagina- 

 tion. In the 

 eggs of these 

 insects, as 

 growth pro- 

 ceeds farther, 

 the embryo 

 turns in the egg 

 and reverts to 

 its original 

 position on the 

 ventral face (fig. 

 60 C). In the 

 Ion g-h o r n e d 

 Grasshoppers, 

 another mem- 

 brane is formed 

 between the 

 serosa and the 

 /«), which arises 



