DIGESTIVE ORGANS. 



d 



he mouth is furnished with a long trunk 

 (fig. Hj d} rolled spirally, composed of b a 



two filaments hollowed into a gutter on the ; 



internal side, which are in fact the jaws 

 excessively elongated and modified in form. 

 At the base of this lube, we observe in front 

 a small membranous piece which is the 

 representative of the labrum, and, on each 

 side, a small tubercle, the last vestiges of 

 the mandibles. We also perceive in the 

 same situation the rudiments of the maxil- 

 lary palpi (e), and behind we find a little e 



triangular lip bearing two very long labial p^ n BEAK OF A 



palpi, composed of three articulations, al- BUTTERFLY. 



most always hairy and furnished with scales. 



44. The digestive tube (fig. 12) is always open at both ends, 



and extends from the mouth 

 to the anus ; sometimes it is 

 straight, at others, more or 

 less flexuous ; and here, as 

 in animals of a higher order, 

 it is very short in carni'vor- 

 ous insects, and very long in 

 those species which feed on 

 vegetable substances. Some- 

 times it preserves nearly the 

 same diameter throughout its 

 whole length ; but, generally, 

 it presents enlargements and 

 contractions which enable us 

 to distinguish an O3sophagus, 

 a stomach and an intestine. 

 Sometimes we find several 

 stomachs (jf, #, h) which 

 have been named, crop, giz- 

 gard, and chyliferous ven- 

 tricle. 

 Fig. 12. DIGESTION OF INSECTS. 45. On each side we see 



Explanation of Fig. 1 1. Beak of a butterfly ; a, the head ; ft, antenna ; 

 c, the eye ; d, proboscis or trunk spirally rolled ; e, rudiment of maxil- 

 lary palpi. 



Explanation of Fig. 12. Digestive apparatus of an insect; a, the he id, 

 6 the antennae; c, the mandibles; d, the palpi; e, the oesophagus ; 

 /, g, h, the stomachs ; i, the intestine ; j, the rectum ; A:, the biliary ves 

 sels; /, secreting organs ; m, the anus. 



44. What are the characters of the digestive organs in insects ? For 

 what is the digestive tube of carm'vorous insects remarkable ? Of what 

 parts do the digestive organs consist ? 



45. What are biliary vessels" 



