MUb(^nuci^, ^iLf^tvuKivi^, ^nD DRAGON-FLIES 5 



note the eyes (two small black spots), the feelers, or 

 antennae, and a pair of tufts or brushes of hair on the head 

 which vibrate rapidly and constantly. These brushes by 

 their vibration create currents in the water setting toward 

 the mouth, which lies between them, and thus bring food 

 to it. This food consists of any tiny animalcules and 

 microscopic bits of organic matter in the water. Are 

 there any legs or wings .'' Examine the posterior 

 end of the body and note its division into two parts — 

 one the end of the hind body or abdomen, the other a 

 breathing-tube projecting from the next to last body- 

 ring. Make a drawing of the larva, showing and naming 

 all these parts. 



Observe again the larvae in the jar. When they hang 

 from the surface note that only the tip of the breathing- 

 tube reaches it. Note the vibration of the mouth-brushes. 

 The larvae feed busily for most of the time. If they sink 

 in the water when they stop "wriggling," i.e., swimming, 

 how is it that they can rest quietly at the surface .'' For 

 this reason : the tip of the stem-like breathing-tube pro- 

 jects slightly above the surface when the wriggler comes 

 up to breathe, so that the expanded edges of its mouth 

 are caught by the tense surface film and the wriggler's 

 body being but slightly heavier than water, is thus sup- 

 ported or suspended by the film. It is easier to prove 

 the existence of this film than to explain it. If you care- 

 fully lay a clean needle on the surface of the water it 

 will not sink, although much denser, i.e., heavier than 

 water, but will be supported by the surface film. If you 

 fill a tumbler to its brim you can still add more water 

 carefully and so heap it up above the level of the brim. 

 This is because the surface film extending over the water 

 from edge to edge holds it in place. If you dip your 

 finger in and then lift it up the water does not all run off, 

 but a large drop will remain hanging to your finger. 



