74 DIGESTIVE ORGANS. 



the " caecum " lie evidently means the rectum. Nicolet 

 gives his description of these parts as applicable to the 

 order generally, and does not mention which genus or 

 genera he particularly examined. In those which I 

 have dissected, and particularly in Tomocerus, Orche- 

 sella, and Smynthurus, the digestive organs pass 

 straight through the body without any circumvolutions 

 from the head to the tail, and fall into three divisions, 

 the oesophagus, the stomach, and the rectum. I think 

 there are no Malpighian vessels. 



Von Olfers, the only naturalist who has, since my 

 paper in the ' Linnean Transactions ' (which, however, 

 he does not appear to have seen), occupied himself 

 with the anatomy of the Collejibola, also describes 

 and figures the intestinal canal, at least in OrcheseUa, 

 as a straight tube passing directly from one end of 

 the body to the other, and falling into three divisions, 

 the oesophagus, the ventriculus, and the rectum. 



The oesophagus is rather long, narrow, and com- 

 posed of an inner chitinous membrane thrown more 

 or less into folds, and a cellular enveloj3e, outside 

 which, again, is a loose and very delicate membrane. 

 Nicolet describes a crop as existing between the 

 oesophagus and the stomach ; but he admits that 

 it is only " une simple dilatation de I'csophage, dont 

 le diametre varie selon que I'insecte a plus ou moins 

 mange." 



Von Olfers was, I believe, the first to observe that 

 from one side of this swelling, which is somewhat 

 thickened, rises an elongated membranous tube. This 

 he regards as the salivary gland ; and he considers 

 that it really rises immediately behind the mouth, 

 passing backwards along the oesophagus, to which, 

 however, it is so firmly attached that " ne vi quidem 

 separari possint " (they can hardly be separated 

 even by force). In fact, if the "salivary gland" 

 and the stomach be pulled in opposite directions, as 

 far as my experience goes, the former gives way. 



The stomach is capacious, and extends in a straight 



