76 



NATURE STUDY 



Fig. 49. 



view show 



ed under-lip. 



Examine, also, the thin flat blade or oar-like processes at the poster- 

 ior extremity of the slender- bodied young dragon-flies. Thes 

 are tracheal gills for breathing, and with a magnifier the fine dark 

 branching air-tubes (tracheae) can be seen in them. 



Observe now the young dragon- 

 flies in the aquarium. If there are 

 some soft-bodied insects in the 

 water, you will not have to watch 

 long before you can see the grasp- 

 in S Y ?a S cor r fd"by J [i le foTd l ing lower-lip at work. As anun- 

 suspecting insect swims by the 

 masked face of the young dragon-fly, like a flash the lower lip 

 darts forward and those two fine-toothed grasping flaps at the tip 

 seize the insect, and carry it, as the lip folds up again, to the 

 strong jaws of the captor. The young dragon- 

 flies are very voracious, and they will soon capture 

 and eat most of the other soft bodied insects in the 

 aquarium. 



The eggs of the dragon- flies are either drop- 

 ped into the water by the females which fly about 

 over the pond, or are placed in slits cut into the 

 stems of water plants. The young dragon-flies 

 live for from a few months to nearly a year, gradu 

 ally growing larger, and the wings slowly develop- 

 ing. When ready to transform, the young dragon-fly crawls up 

 on the stem of some water plant or projecting stick or stone, out 

 of the water; the skin breaks along the back, and slowly 

 the winged dragon-fly issues. This transformation takes place 

 usually in the early morning hours, and this cannot be conven- 

 iently observed by the class. If you bring into the aquarium, - 

 however, a number of young dragon-flies at the time of year 

 (the late spring and early summer) when they are transforming, 

 the process may be observed in the school-room. 



