78 THE WEAPON OF DEFENCE 



curve over outwardly, until at their extremities 

 they are attached to a lever, which works on 

 a pivot. It is sufficient to say that to this lever 

 are attached powerful muscles, the action of 

 which causes the lever to turn on its pivot. 

 The net result of this arrangement is somewhat 

 similar to that produced by a revolving wheel. 



We know that the rim of a wheel must revolve 

 much more rapidly than the hub, so that, suppos- 

 ing the pivot on which the levers turn to represent 

 the hub and the curved upper ends of the lancets 

 the rim, it will be understood that if the turning 

 of the lever on its base is rapid, that of the lancets 

 will be still more so. This is why the bee is 

 enabled not only to insert its sting very quickly, 

 but also to compel it to penetrate such hard 

 substances as leather, notwithstanding its extreme 

 delicacy. 



The movement of these lancets forces a 

 quantity of poison down their hollow centres, 

 by the contraction of a bulbous enlargement at 

 the upper end of the sheath. This bulb is not 

 the main reservoir of the poison. This is situated 

 further up, and is connected with the bulb by a 

 pipe, through which it automatically supplies the 

 bulb with poison to replace that driven out. 



The exact nature of the poison is not quite clear. 

 Some have supposed it to be simply formic acid ; 

 but, although this is doubtless the base of it, 

 there are other ingredients, said to be very power- 



