THE ORGANS OK DIGESTION. 151 



at its commencement and end ; a short, narrow ilium ; a broad., sack- 

 shaped thick-intestine ; and a tolerably long but not broad colon : the 

 beetles have a very long but narrower cylindrical stomach, an ilium 

 resembling that of the larvae, a much narrower, gradually distending, 

 thick-intestine, and a longer cylindrical colon, which distends very 

 widely close to the anus. In both cases, consequently, the intestinal 

 canal is longer in the perfect state than in the larva, but in the vege- 

 table feeders more considerably so than in the carnivora, in which it, 

 namely in Dylicus, is shorter. Whereas the beetle has a much more 

 complex intestine, and more organs to effect the change and trans- 

 formation of the food than the larva, which is the more remarkable, 

 as both, at least generally, take the same food, which is not always the 

 case in the other orders, for example, in the Lepidoptera and flies. 



115. 



II. THE FATTY MASS, OR RETE. 



The fatty mass of insects is a web of generally white or yellow 

 ragged or stringy substance interwoven in every possible way, enve- 

 loping the intestinal canal and the organs connected with it, as well as 

 all the other internal parts, but it is never in direct immediate connec- 

 tion with any organ. It receives its name from its undeniable resem- 

 blance to the fat of the higher animals, and which is expressed in the 

 above peculiarity, and even more strongly in other circumstances. It 

 thence appears that it forms no portion of the intestinal canal, being no- 

 where in connection with it, but as it is the produce of digestion and 

 as it is increased or decreased by the perfection or imperfection of the 

 function of digestion, it must therefore, as standing in relation to the 

 organs of nutriment, be treated of and described when treating of them. 

 We are the more strongly impelled to this by the opinion expressed by 

 Oken, and which Treviranus has recently supported by analogies, that 

 the fatty mass of insects must be considered as their liver. Indeed in 

 the scorpion a substance similar to the fatty mass stands in connection 

 with the nutrimental canal by means of vessels, but they possess 

 besides two twisted biliary vessels, which likewise here and there quit 

 that substance. In all true insects, however, we find no such close 

 connection of both organs, and if it cannot be denied that the fatty 

 mass is of importance to digestion, and that much nutrimental matter 

 is derived from it, yet this admission proves by no means its analogy 

 to the liver. In fact, it is neither absolutely liver nor gland, but 



