0/0 ZOOLOGY. 



destined to secure a depot for the eggs of the insect in a 

 place adapted for the development of the young. The sting 

 of the wasp and bee is formed of two sharp stylets, lodged in 

 a horny stalk or sheath, having each a furrow, along which 

 flows the poison secreted in a small gland situated close to it. 

 In the state of repose, the whole apparatus is drawn within 

 the body of the animal ; but when the insect wishes to use it, 

 the sheath is protruded, and along with the sting is driven 

 into the skin of its enemy. Sometimes it is impossible to 

 withdraw it, and the whole sting separates then from the 

 body, remaining implanted in the wound, causing the speedy 



death of the insect. The 

 male is always stingless, 

 and thus can be handled 

 without danger; but the 

 female and the working 

 bee are provided with it, 

 and its sting produces a 

 very painful inflammation. 

 The auger of the foenus 

 (Fig. 353), of the ichneu- 

 mons, and of many other in- 

 sects, has a somewhat analo- 

 gous arrangement ; and we 

 remark also, in general, a 

 serrated edge, by which it 

 divides the entrails of the 

 animal or the tissue of the 

 vegetable in which it pur- 

 poses depositing its eggs. 

 It is by piercing in this manner an oak of the Levant, that a 

 small insect called cynips gives rise to the formation of the 

 gall-nut, of which so much use is made in the fabrication of 

 ink and in the preparation of dark dyes. The small fissure 

 produced by the auger of the insect gives rise to an effusion 

 of vegetable juices, and this produces an excrescence, in the 

 centre of which may be found the eggs of the cvnips. 



518. Insects have the organs of sense highly developed; 

 they possess sight, smell, as well as tact, taste, and hearing ; 

 but hitherto the organs of olfaction and audition have not 

 been discovered : but little is known of the organ of taste. 

 The structure of the eyes differs very much from that of the 

 higher order of animals. In general, the organ which at 



Fig. 353. The Fcenus. 



