WINGS AND FLIGHT. 



147 



tracheae contain at the time. They are at rest, the 

 blood is moving slowly, the body is specifically heavy, 

 and the muscles are not braced up ; but after the 

 wings have been lifted, and a few energetic move- 

 ments of the abdomen made, the vesicles and tracheae, 

 which just before were flat as ribbons, get filled, 

 and the bee sails away. In many practical opera- 

 tions, bees may be shaken down from their combs in 



J3WI/V 



Fig. 31.— Longitudinal Section through Thorax of Drone 

 (Magnified Seven times). 



LA Levator Alse (Wing-raising) Muscle, showing Fasciculi, or Fibre Bundles; 

 DA, Depressor Alae (Wing-lowering) Muscle ; A, Antagonist of Depressor ; 

 mom. Posterior Wing Muscles ; mp, Mesophragma ; as, Air Sacs ; No. 3, Gland 

 No. 3 ; c, Cervical or Neck ; h, Part of Head. 



a mass, scooped up in spoons or shovels, and weighed 

 and measured in open vessels, pretty much like seeds ; 

 the facts just recounted going far to explain the reason. 

 The utility, beyond the purposes of flight, of filling up 

 with air, and the method of its accomplishment, are 

 both interesting and curious. Fig. 31 gives a section 

 through the thorax of the drone, showing the muscles 

 of flight, surrounded on all sides by air sacs (as), from 

 which pass very numerous tracheae (page 42), supply- 

 ing the abundant oxygen these most active muscles re- 



