350 PHYSIOLOGY. 



same, c, c.) stand in close connexion, as well as the four-jointed max- 

 illary palpi (c, f.), at the base of these maxilla?, whereas the three- 

 jointed labial palpi hang in front of the apex of the labium closely to the 

 bone of the tongue (the same, f. 11.^ /!). We consequently find all 

 the organs of mandibulate insects, and yet nothing is more certain than 

 that the Phryganea do not bite, but only suck. Their food consists 

 of the sweet juices of flowers, and we meet Avith the perfect insect only 

 upon flowers, particularly upon the umbelliferce, .syttgcnistce, nymphece, 

 and similar plants, which grow in the vicinity of water, whereas the larvaa 

 live in water and have distinct and separate manducatory organs, and 

 prey upon other minute water insects. 



We now proceed with the general mode of taking food in haustellate 

 insects. Their oral organs are thrust into the material which supplies 

 them with food, and is sucked by means of the sucking stomach through 

 the canal formed of the labrum and labium. The suckina; stomach, 



O 



according to Ramdohr's * representation, is a double bladder-shaped 

 appendage at the lower end of the oesophagus. When distended the 

 air within it, as in the oesophagus, is rarefied, which causes the ascent 

 of the juices of flowers into the oral tube ; it then comes into the 

 oesophagus, which swallows it into the stomach, and this continues so 

 long as the sucking bladder is distended, and only upon its contraction 

 does it cease. This sucking stomach is found (see 103) in almost 

 all insects provided with haustellate organs, and by its distension 

 the ascent of the liquid nutriment is occasioned. It appears to be 

 peculiar to haustellate insects, and to present itself in this form in no 

 other animals. The swimming bladder of fishes only has by its open- 

 ing into the oesophagus some resemblance to the sucking stomach of 

 the Diptera, and Treviranus t therefore compares it with that organ, 

 a parallelism which, although not supported by the functions of the 

 two organs, yet by their corresponding situation, form, and struc- 

 ture deserves consideration. The other Diciyotoptera, as Hemcrobius, 

 Myrmecoleon, Ascalaphns, and Semblis, have no sucking bladder, and 

 therefore do not suck, but bite. They are in general carnivorous, and 

 are therefore made. to bite and manducate their food. 



The wasps and the bees may be classed next to the Phryganea, from 

 their mode of sucking their food. The conformity is greatest in the wasps. 

 Their labium and maxillae form a similar apparatus, but they arc pro- 



Verdauungswerkx. PI. XVI. f. "2. f Vrnnisclite Sclirilieii, vol. ii. p. 15(1. &c. 



