TUBE OF THE HOOKAH. 377 



veyed into the system of an insect. These breathing-tubes 

 ramify to every portion of the body of an insect, even pene- 

 trating to the extremities of the antennse, the wings, and the 

 legs. It is obvious that as these organs are in tolerably con- 

 stant movement, and the legs are much bent at every joint 

 by the action of walking, the air-tubes which run through 

 them must possess the same qualities as those of the gas-lamp 

 and diver. 



If one of these tracheae be removed and placed under the 

 microscope, it will be seen to be constructed in a manner 

 exactly similar to that which has been described. Within the 

 membrane which forms the tube proper there is a very fine, 

 but very strong thread, which is coiled exactly like the wire 

 spring. It is not attached to the membrane, and so strong is it 

 that, although it is all but invisible to the naked eye, it can be 

 drawn out as shown in the left-hand figure of the illustration. 



TRACHEA OP DRAGON-FLY LARVA. TUBE OP HOOKAH. 



If laid on a piece of glass, it immediately tries to recoil itself, 

 and for some little time will twist and curl about as if it were 

 alive. 



On the above illustration are two similar examples of 

 the spiral thread with a flexible tube. The right-hand 

 figure represents one of the many forms of the water-pipe, 

 whether known as Hookah, Narghile, or Hubble-bubble. In 

 the simpler forms of this pipe, such as the latter, the inhaling- 

 tube is quite straight, and the bowl is held in the hands of the 

 smoker. In the more refined pipe, however, the tube is very 

 long, flexible, and made elastic by an inner spiral wire. 



Perhaps the reader may remember that the larva of the 

 Dragon-fly is a most remarkable creature in consequence of 



