THE LOCUST OR SHORT-HORNED GRASSHOPPER 353 



Body Wall and Hcemocode. — Removal of the dorsal skeleton 

 and underlying tissue discloses the digestive tract and other internal 

 organs lying in a cavity which is a hcemocoele and not a true body 

 cavity or coelome. Within this cavity, or attached to the body 

 wall, are the internal organs. The spaces of the haemoccele between 

 the organs are largely occupied in the adult insect by an irregular 

 mass of tissue known as the fat-body, which is the principal place 

 of food storage. In insect larvae, such as the caterpillars of 

 the moths and butterflies, the fat-body becomes greatly devel- 



FiG. 176. — Anterior end of locust showing digestive and nervous systems. 



an, antenna; an.n., antennary nerve; br, brain; c.e.c, circum-esophageal connective; 

 cr, crop; e, esophagus; f.g., frontal ganglion; hy, hypopharynx; l.n., labral nerve; md, 

 mandible; oc.n., nerve to eye= and ocelli; op.g., optic ganglion; s.d., salivary duct; s.e.g., sub- 

 esophageal ganglion; t.g.l, first thoracic ganglion, (.\fter Snodgrass, Educational Publica- 

 tions No. 2, Washington .\gr. Col.'> 



oped as the larva stores up food against the time of its meta- 

 morphosis. Parasites that invade the body cavity of such insects 

 feed principally upon this accumulated food of their hosts. 



Digestive Systetn. — The alimentary canal is almost a straight 

 tube, extending from mouth to anus (cf. Figs. 176 and 180), 

 although it is modified in different regions. The hypojjJiarynx, 

 arising from the base of the labium and just posterior to the mouth, 

 has been mentioned in the account of the mouth parts. Upon the 

 inner surface of the labium is a slightly elevated area, on which 

 is located the sense of taste. The space included by the oral 

 appendages might be called a buccal cavity since it contains the 



