60 



ZOOLOGY. 



in a sheath, the whole forming a tube through which the 

 egg passes to its destination. In the working bees and 

 wasps a similar tube forms the " sting," which not only 

 makes a wound, but inserts poison therein. 



Other insects are furnished with bristles at the ex- 

 tremity of the body. These, in the spring-tails, assist in 

 leaping. 



71. Digestion. 

 Some insects, such 

 as the beetles, mas- 

 ticate their food ; 

 others, like the but- 

 terflies, subsist by 

 suction. The or- 

 gans of the mouth 

 are varied to suit 

 these different func- 

 tions. In a beetle 

 there are two lips, 

 an upper (labrum) 

 and a lower (labi- 

 UHl), closing the 

 mouth above and 

 below ; and two 

 pairs of hooked and 

 toothed jaws, which 

 work horizontally. 

 The upper jaws are 

 termed mandibles. 



a, head and mouth ; &, salivary glands ; c, ceso- -j i 



phagus ; e, crop ; h, stomach ; k, Malphigian ana are 

 canals representing the liver ; I, poison gland, biting j the lower 



are called maxillae, their office being to masticate the 

 food. 



The lower lip, which is believed to consist of a second 

 pair of maxillse united together, and the lower pair of 

 jaws, bear each one or two jointed filaments termed palpi 

 (Lat. palpOy I touch), which are supposed to be organs of 

 touch. 



Fig. 22. DIGESTIVE APPARATUS AND POISON 

 GLAND OF THE BEE. 



