iiS 



THE HONEY-BEE. 



which are coils of an elastic thread, which act like the 

 spiral wire frequently used for keeping open and 

 strengthening india-rubber tubing. By means of this 

 structure the air-pipes'[are maintained in a condition 

 for the free passage of the atmosphere, and if closed 

 by pressure, the elastic fibre reopens them directly 

 the pressure is removed. 



Fig. 34. — a, Air-sacs, 5, Ovaries, of the Queen. 



With regard to the circulation of the nutritive 

 fluid in the system, considerable obscurity prevails. 

 What is known is, that along the back of the insect 

 runs a vessel called, from its position, the dorsal 

 vessel, attached to the outer covering of the body by 

 bands of ligamentous tissue. The portion of this 

 tube contained in the abdomen is enlarged at 

 intervals into chambers communicating with each 



