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170 THE LIFE OF AN INSECT. 



pair of spiracles, or breathing pores, and surround- 

 ing these are placed five minute bristles, which 

 are supposed to act somewhat as a buoy, and to 

 retain the tail in its position. Where 

 the tail joins on to the body of the 

 larva, two tubes thrown into folds are 

 placed, which are connected with the 

 breathing tubes of the tail, at one end, 

 and with the breathing pipes which run 

 along the body of the larva at the other. 

 When the tail is pushed out to its far- 

 thest, these zig-zag tubes are stretched 

 quite straight ; when it is drawn in 

 End of the Tan. again, they are thrown into folds. Both 

 these appearances are shown in the plate. It has 

 been supposed that the larva causes the tube 

 to be pushed out by forcing air into it, and thus 

 causing the zig-zag tubes to straighten themselves. 

 Perhaps the tail is drawn in by the same tubes 

 contracting again, and thus folding together and 

 dragging back the tube to which they are con- 

 nected. 



We need scarcely stop to mention how useful is 

 this admirable contrivance to the insect. Having 

 to seek for their food at the bottom of ditches, 



