218 



LECTURE XVII. 



longer, and is disposed in three or four coils. But in the Orthopterous 

 vegetable-feeding insects^ the canal is characterised by its superior 

 width rather than by its length ; and in them the complications re- 

 quisite for animalizing the food are chiefly manifested by the gastric 

 division. The oesophagus dilates into a wide glandular crop in the 

 cockroaches* and locusts-]-, and has a similar receptacle appended 

 to it in the mole-cricket. J The gizzard has a strong muscular coat, 

 and a callous epithelium, the inner surface of which is beset with 

 projecting teeth or hooks, as in the cock-roach, or with scale-like 

 plates, as in the cricket, generally disposed in longitudinal rows. The 

 tunics of the chj^lific stomach are produced at its commencement into 

 caecal appendages, which augment and complicate its cavity. There 

 are two such caeca in the common and mole-crickets, four in Locusta 

 serratUj six in the migratory locust, and eight in the cockroach. In 

 the coleopterous Buprestidce the stomach is prolonged into two caecal 

 appendages, themselves beset by smaller caeca. 



The gizzard always coexists with the crop, but not always the crop 

 with the gizzard, in insects. All the suctorial species have a crop, 

 either appended to the oesophagus, or forming a preliminary dilata- 

 tion to the chylific stomach. It is of small size in the bug (^Cimex 

 lectularius), and almost obsolete in other Hemiptera. In the bee, 

 {fig. 101.) §, the oesophagus (a), having tra- 

 versed the thorax as a slender tube, dilates in 

 the abdomen into the large honey-bag {b). 

 The valvular funnel-shaped orifice of the chylific 

 stomach (c) projects into the side of the inglu- 

 vial reservoir, and must be withdrawn by a 

 special action, in order to receive any portion 

 of the nectar for the nourishment of the bee 

 itself: it then returns by an antiperistaltic 

 motion, and forms a kind of intussusception in 

 the crop, converting it into the convenient, closed 

 Alimentary canal. Bee. j-eccptacle for the Collected swccts until the bee 

 reaches its hive ; when the honey, having undergone a slight change, 

 which renders it less susceptible of the acetous fermentation, is 

 regurgitated into the waxen cell, and the crop collapses into lon- 

 gitudinal folds. The chylific stomach (<:/) is long, gradually widened 

 to its termination, and transversely plicated. The ileum (e) is short 

 and slender : the colon or rectum (/), wide and capable of great 



* Nos. 607, 608, 609. 

 \ No. 611. 



f Nos. 443. 610. 

 § Nos, 476, 477. 



