INTERNAL ANATOMY OF INSECTS. 109 



wide, it often contains a great quantity of excrement, as 

 the gullet does of undigested food ; but when narrow, 

 the excrement seldom remains long in it. This intes- 

 tine also in a few cases has a lateral enlargement or 

 ccecum (Blind-darm\ being a continuation of the same 

 skin ; but perhaps this enlargement is really analogous 

 to what Ramdohr calls the thick intestine, though in 

 these cases he regards it as an appendage of the rec- 

 tum*. 



I must now call your attention to the bile-vessels of 

 insects. These, by Malpighi b and the earlier physiolo- 

 gists, who regarded them as a kind of lacteals, were de- 

 nominated varicose vessels: but Cuvier and his opinion 

 after some hesitation has been adopted by Ramdohr 

 considers them as vessels for the secretion of bile, and 

 as analogous to the liver of animals that have a circula- 

 tion . As the want of blood-vessels prevents insects 

 from having any gland, the bile is produced with them, 

 as all their other secretions, by slender vessels that float 

 in their nutritive fluid, and from thence secrete the ele- 

 ments proper to form that important product, which 

 usually tinges them with its own yellow hue ; though in 

 the Lamellicorns and Gapricorns they are of an opaque 

 white, and in the Dytisci of a deep brown colour d . Their 

 bitter taste further proves that they contain the bile e . 

 They are long, slender, filiform, tortuous or convoluted, 

 and mostly simple vessels ; sometimes gradually smaller 

 toward the base f , at others towards the apex^. In 



a Ramdohr Anat. 40. 



b DeBombyc. 18. Anat. Comp. iv. 153. 



d Ibid. Ibid. 



f Ramdohr 43, Cicindela campestris, t. iii./. 1. K. 



8 Phryganea grandis, Ibid. t. xvi./. 2. 



