OF DIGESTION, 377 



in the Capricorns, stand in connexion with the intestine at a second 

 lower spot, but do not again open into it, has been shown above ( 111). 

 Joli. M tiller has been misled by Straus to speak likewise of double 

 vessels, which, he says, open at different parts of the intestine *, but 

 such second vessels are not found in any insect. 



224. 



The divisions of the intestinal canal which lie beyond the orifice of 

 the biliary vessels, and which we have described above as the ilium,, 

 clavate intestine, caecum, and colon, occupy a portion of the intestinal 

 canal, which, in the majority of cases, is not half the length of that of 

 the preceding part, and which is indeed often, namely, in the Hemiptera, 

 so short, that it does not form one-tenth of the entire intestine. With 

 respect to the law which regulates the proportions of the parts of the 

 intestinal canal, we may consider that it is in general longer in 

 carnivorous insects, but, on the contrary, shorter in the vegetable 

 consumers, and that the larvae have almost always, with the exception 

 of the larvae of the Dytici, as was remarked above, a very short portion 

 of intestine beyond the orifice of the biliary vessels, whereas in the 

 perfect insect it is longer. 



If we inspect the contents as well as the function of this portion of 

 the intestine in vegetable-feeding insects, for example, in the larvae of 

 the caterpillars, we shall find, according to Rengger's observation, that 

 no further peristaltic motion is detected in it, and that the chyme con- 

 tained within it separates no longer any chyle, nor, indeed, is any mixed 

 with it. In the larvae of the Lamellicornia , no food is observed in the 

 ilium, but the great gut is closely filled with it. This nutriment is 

 found here further comminuted and more pappy than in the stomach, 

 differing in about the same proportion as the chyme of the stomach does 

 from that of the caecum in the Rodentia, and we must, therefore, at 

 least in this instance, admit of a repeated separation of chyle, which is 

 also confirmed by the dry, thick, excrementitious contents of the short 

 colon. Ramdohr supposes that the biliary vessels, from their in general 

 ascending and descending the duodenum, but subsequently spreading 

 themselves about the greatest convolutions of the ilium, imbibe from it 

 nutritive matter during the passage of the chyme, and that it is thence 

 that the latter contains less moisture in the ilium : he ascribes the same 



/ 4? 



DC Glatulul sec. Str. par. pp. 68, 69. 







