ORTHOPTEROIDEA (PANORTHOPTERA) 237 



It thus shifts its position from the ventral to the dorsal surface of the egg; 

 and the embryonic head, which originally pointed toward the posterior 

 pole of the egg, turns toward the anterior pole. 



The corpora allata arises soon after blastokinesis as a pair of invagina- 

 tions of the lateral body wall of the embryo on either side of the 

 intersegmental region between the mandibular and the first maxillary 

 segments. The bhnd ends of these invaginations are directed medioven- 



bl ^'^ cbl 



■mus.s 



oen 



mus 



nc 



Fig. 159.— Locusta. Cross section of fourth abdominal segment one day after blasto- 

 kinesis. (bl) Blood cells, {cbl) Cardioblasts. (drc) Definitive dorsal closure. (/) Fat. 

 {g) Gonad, (mus) Muscle, {mus. s) Suspensory muscle of the heart, (nc) Nerve cord. 

 {oen) Oenocytes. {pd) Paricardial diaphragm, {splm) Splanchnic mesoderm, {st) 

 Stigmata, {vs) Ventral septum. 



trally. They soon become rounded and eventually are severed from the 

 outer ectoderm. They then move dorsally and posteriorly and come to 

 lie on the stomodaeum. Their connection with the stomatogastric 

 nervous system is purely secondary. 



Of the four pairs of cephaHc invaginations, the first three, respectively, 

 arise in front of, at the level of, and behind the mandibles, and the fourth 

 pair arises behind the first maxillae. The first and third pairs form the 

 tentorium; the second forms the mandibular apodeme; and the fourth 

 gives rise to the salivary glands. In the 90-hour stage a pair of small, 

 backwardly directed T-shaped invaginations arise between the mandi- 

 bles and the rudiments of the intercalary appendages. At the same time 



