4^0 THE INSECTA. ^ 339. 



whether one of the pairs of these glands with these Ileniiptera, may not be 

 a poison apparatus. 



The Inscc-ta have no distinct Hepatic Organs, but the function of a Liver 

 is performed by the walls of the stomach, the internal tunic of which is 

 composed of closely-aggregated hepatic cells. With many species whose 

 stomach has caeeal appendages, the walls of these last have a similar hepatic 

 structure, and must secrete, therefore, a bile-like fluid.^"^ 



With some Insecta, the ileum has glandular appendages, whose product 

 is perhaps analogous to a, pancreatic fluid. The two or four rows of fol- 

 licles which, as before mentioned, are situated on the ileum of the Penta- 

 tomidae and some Coreidae, would, in the same manner, be regarded as a 

 Pancreas. The same remark applies to the ramified appendages, which, 

 with Gryllotalpa, open into the stomach below the two caeca, as well, also, as 

 to the two or three follicles which, with Pyrrhocoris, are inserted, laterally, 

 on the posterior part of the ileum. ^'^' 



There is found, with all Insecta, a Corpus adiposum, — a tissue, composed 

 of adipose cells, which is intimately connected with the functions of digestion 

 and assimilation. This body is especially developed towards the end of 

 the larval state, and it disappears, for the most part, during the pupa 

 period, so that only a few traces of it are found with Insecta in their per- 

 fect state. It is usually of a white, or a dirty-yellow color, but is also 

 observed of a green, red, or orange hue. In the larvae, the fat cells gen- 

 erally form pretty large, lamelliform lobes, sometimes ramified or reticu- 

 lated, sometimes plicated, spread through the abdominal cavity in all the 

 intervals of the viscera. These lobes are always traversed and retained 

 in place by numerous trachean branches. With the perfect Insecta, the 

 remains of this body are not usually found except in the posterior portion 

 of the abdominal cavity, where they consist of fat-cells loosely scattered, 

 and not retained by the tracheae. ^-°> 



18 For these biliary organs, see J. Mailer, De sur les Hi^miptires, p. 44, PI. II. fig. 19, 21 (,Pyr- 

 Glanil. struct, p. 67. The Malpishian vessels rhocoris).\ 



which were formerly regarded as biliary tubes, 20 gee /y. JOrz/our, Recherch. sur les Carabiq.,in 



will be treated of in future {^ 346).* the Ann. d. Sc. Nat. VIII. 1826, p. 29 ; Recherch. 



19 See L. Du/our, Recherch. sur les Orthoi)t. p. sur les Ilcmipt. p. 141, and Recherch. sur lea 

 332, PI. II. fig. 19 (firyllotalpa), and Recherch. Orthopt. p. 291, 385, 562.J: 



* [ § 330, note 18.] The liver of the Insecta, as closely applied to the intestinum tenue ; they join 



well as that of the Invertebrata generally, has been the intestine at the junction of the duodenum and 



investigated by Will (Muller's Arch. 184S, p. 502) ileum. — Ed. 



who has applied the same chemical mode of in- f [ § 339, note 20.] See, upon the Corpus adU 



quiry, as that of Brugnatelli and Wurzer upon posiim, Mayer (reber die Entwickelung. des Fet- 



the Malpighian vessels showing their urinary char- tkorpers, &c. bei den Lepidopteren, in Siebold 



acter (see infra § 345, note 2). With the Insecta, and KblUker's Zeitsch. I. p. 175) who has traced 



he regards as hepatic the caeeal and other glandu- its develojiment. 



lar appendages which, when present, lie upon the These adipose bodies are formed from a great 



6T-called r-^entriculua, thus confirming the suppo- number of separate, flattened, usually many- 



sition e.xpressed in the foregoing note. For the in- pointed lobes. These lobes consist of pouches with 



timate microscopic structure of the liver of the In- structureless walls, and filled with fat-globules, 



secta, see Leidy, Amer. Jour. Med. Sc. XV. 1848, Each pouch is originally a simple cell with a largo 



p_ 1_ Ed. nucleus attached to its wall. In this cell are 



t [ § 339, note 19.] For the hepatic organs of formed daughter-cells, which, when filled with fat, 



Belustoma see Leidy, loc. cit. p. 63, PI. X. fig. burst, and thereby the motlicr-cell becomes the fat- 



4, i. They consist of four long very tortuous tubes containing sac. — E». 



