378 LECTURE XVII. 



pendages, themselves beset by smaller caeca. In the water-beetles a 

 longish csecum extends forward from the rectum. 



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 

 dilatation to the chylific stomach. It is of small size in the bug 

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

 bee {fig. 151)*, the oesophagus (a), having traversed the thorax as 

 a slender tube, dilates in the abdomen into the 

 large honey-bag (6). The valvular funnel- 

 shaped orifice of the chylific stomach (c) pro- 

 jects into the side of the ingluvial 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 and must be withdrawn by a special action, in 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 re- 

 turns by an antiperistaltic motion, and forms a 

 kind of intussusception in the crop, converting 

 it into the convenient, closed receptacle for the ^(7' 



collected sweets until the bee reaches its hive : ..."^ * . « 



' Alimentary canal. Bee. 



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 (c?) is long, gradually widened 

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

 and slender : the colon or rectum {f), wide and capable of great 

 distension. The bees on which Hunter experimented f endured a 

 long confinement, but could not be compelled to foul their hive ; as 

 soon as liberated, they rose in the air and disburthened their over- 

 laden cloaca. 



In the Lepidoptera {fig- 160.), the ingluvies projects, like a bag, 

 from the side of the oesophagus {j) ; and in the ZygcencB it is divided, 

 as in the pigeon, into two equal parts. The chylific stomach is very 

 small, but is sacculated, and, according to Meckel, is shaggy in the 

 death's-head moth. The small intestine (/) is longer and more con- 

 voluted than in the bee ; the large gut (m) is short and wide. 



In the Diptera the crop J, though situated upon the stomach in 

 the abdomen, is appended by a long and slender neck to the be- 

 ginning of the narrow oesophagus. The lower end of the oesophagus 

 expands into the chylific stomach, the cardia being sometimes marked 

 by a callous ring, which is the remnant of a small bladder existing there 

 in the larva. The small intestine is convoluted ; the rectum short 



* Nos. 476, 477. f CCXLVI. p. 176. % Prep. No. 596. 



