STRUCTURE, GROWTH AND ECONOMICS OF INSECTS 25 



Fig. 29. — Digestive canal of Gryllus pennsylvaniciis. sd., Salivary duct; Oes., 

 oesophagus; Sg., salivary gland; C, crop; pv., pv.", proventriculus; gc, gastric caeca; 

 m., mesenteron; Mv., valve between two divisions of the mesenteron; gl., digestive 

 glands; il., ilium; u.d., duct of malpighian tubules; ut., malpighian tubules; Col., 

 colon; rt., rectum; An., anus. 



