THE GENEALOGY OF THE BEE 3 



who have succeeded in constructing engines which 

 develop a high power with very little weight. 



It is obvious that there must be some other 

 reason than mere size of wing to account for the 

 powerful and direct flight of the bee. Doubtless 

 shape has much to do with the matter. In the 

 butterflies and moths, the swiftest fliers, such as 

 the " hawk " and " swift " moths, have long, 

 pointed wings, and in the bees we observe the 

 same character. The broadest portion is very 

 close to the base, while the tip is fined off to an 

 absolute point. 



Another striking character of hymenopterous 

 wings, especially those of bees, is the great thick- 

 ness and rigidity of the anterior margin, the front 

 boundary of the wing. Every wing is made up 

 of two layers of membrane, one above and one 

 below. These membranes are supported by 

 a framework of tubing, known to entomologists 

 as " nervures," and these nervures are filled with 

 air during flight. The result of this arrangement 

 is that the wing is kept as taut as a drum, and 

 thus offers the greatest possible resistance to air 

 pressure. 



But even this well- designed mechanism would 

 be insufficient to serve the purpose of such 

 prolonged and powerful flights as are undertaken 

 by bees were it not allied to exceptional motive 

 power. This motive power is supplied by ex- 

 tremely rapid vibrations of the wings. The 



