The Wings 6i 



With its marvellous engine run by vital force in opera- 

 tion, it can go where it listeth ; and while tlie more helpless 

 butterfly is often blown about at the mercy of the wind, its 

 gorgeous wings even serving as sails to catch the breeze 

 and carry it far out to sea, the bee, like a trim little steam 

 launch, heads up against the wind, and goes where it 

 pleases. 



The exact manner in which the wings are used as organs 

 of progression, raising the bee from the earth, speeding it 

 in any direction, with or against the wind, taking it high in 

 the air, or dropping it with lightness and accuracy upon 

 a selected flower, is still a problem for philosophers to 

 puzzle over. 



There is no doubt that the flight of the bee is aided, 

 perhaps rendered possible, by a very wonderful system of 

 air-sacs and air-tubes. 



There are large air-sacs in the upper end of the abdo- 

 men, almost filling it when distended with air, and there 

 are air-sacs at the bases of the wings. These air-sacs open 

 to the surface by minute orifices called spiracles, one at the 

 base of each of the four wings, and several others open on 

 the sides of the abdominal walls. 



The bee, like the bird, is supplied with air-cavities to sus- 

 tain it in its flight, and these air-cavities are also its " lungs." 



It pumps the air into them by a continuous motion of 

 the abdomen when at rest, and has the power to close the 

 spiracles, and thus shut in a large amount of air when it 

 desires to fly. 



Packard tells us that the insect can change its specific 

 gravity by filling or emptying its air-sacs, and that increased 

 exertion causes increased activity in breathing, while de- 

 creased exertion has of course the opposite effect, so that 

 in hibernating insects respiration is almost entirely sus- 

 pended. He also says that the air rushes into the thoracic 



