176 ORGANS OF DIGESTION. 



siderable, opening into a bag situated before the esophagus, 

 into which it leads ; the function of this bag appears, ac- 

 cording to Burmeister, to be simply the rarefaction of its 

 contained air, by which fluids in the proboscis and esopha- 

 gus are pumped up into the first stomach. Insects pro- 

 vided with organs of mastication are deprived of this suck- 

 ing apparatus ; so that the development of maxillae and suc- 

 torial instruments stand in an inverse ratio to one another. 

 Burmeister is of opinion that, in insects deprived of a pro- 

 boscis, the sucking bag is converted into a crop. The 

 digestive organs of coleopterous insects present considerable 

 variety in their structure ; two sections of the order are 

 formed on this difference alone ; to the one section belongs 

 those which have a globular muscular stomach, and short 

 intestinal canal ; to the other, those having a large mem- 

 branous stomach, furnished with caeca, and a long tortuous 

 intestine : the first group are carnivorous, the second phyto- 

 phagous. 



In Cicindila campestris, a carnivorous beetle, belonging 

 to the first group, the short esophagus is dilated into a 

 large glandular crop, opening into a small muscular giz- 

 zard, furnished internally with horny teeth, to perforate, 

 rub down, and divide the aliments. In this muscular sto- 

 mach we recognize a repetition of the type already described 

 in some mollusca. To this organ, called by Ramdohr the 

 plaited stomach, succeeds a flask-shaped chylific organ, fur- 

 nished with a number of small glandular follicles, for secreting 

 the gastric juice ; at the point where this organ emerges 

 into the pylorus, the ramified biliary vessels enter its cavity 

 by four ducts ; the intestine is short and straight, and de- 

 velops a large muscular colon, soon terminating in an anal 

 aperture. 



The Melolontha vulgaris (common cockchafer) is an ex- 

 ample of the structure of these organs in the coleoptera, com- 

 prised in the second group. Here we find the entire canal 

 much increased in length and diameter ; in this vegetable- 

 eating insect the glandular organs are more voluminous, and 

 from the sides of the ramified vessels numerous csecal appen- 

 dages are produced. The esophagus is dilated into a membra- 

 nous crop ; the gizzard is merely rudimentary ; the stomach is 

 in the form of a long glandular sac, twisted in a spiral man- 



