6 CLASS INSECTA. 



when they are very much dilated at their extremity, the 

 principal part. The tongue may also have something to do 

 with this function. 



A preparatory or buccal apparatus, the intestinal canal, 

 the biliary vessels, also named hepatic, those which are 

 called salivary, but which are less general, those free or 

 floatins; vessels which have received tbe denomination of ex- 

 cremental, the epiploon, or corpus adiposum, and probably 

 also the dorsal vessel, may be said to constitute the digestive 

 system. It is singularly modified according to the diversity 

 of aliments, or it forms a great number of peculiar types, 

 which we shall describe in treating of the families of this 

 class. We shall at present only say a word respecting the 

 buccal apparatus, and the principal divisions of the intestinal 

 canal, beginning with the last. In those insects, such as the 

 carnassial coleoptera, in which it is more complicated, we 

 may distinguish in it the pharynx, the sesophagus, the crop, 

 the gizzard, the stomach, or chylific ventricle, and some in- 

 testines, which are divided into the slender intestine, the thick 

 intestine, or coecum, and the rectum. In the insects in 

 which the tongue, properly so called, is attached to the an- 

 terior or internal face of the lip, or where it is not disengaged, 

 the pharynx is situated on this same face, which is generally 

 the case. We shall also add, that, with respect to the biliary 

 vessels, a naturalist to whom we are indebted for the first 

 valuable observations on the respiratory organs of the my- 

 gale, M. Gaede, professor of natural history at Liege, does 

 not consider these vessels as secretory, according to the com- 

 mon opinion ; but his notion does not seem to be sufficiently 

 well founded, and the observations of M. Leon Dufour even 

 appear to destroy it.* 



* This last mentioned naturalist, whom I shall often have occasion to 

 quote, has explained in the most minute manner every thing which has 



