300 DRAGON-FLIES. 



drawn gently into the tube, and expelled with greater or 

 less violence, thus driving the insect forward exactly on 

 the principle of the rocket. 



Were it not for this wonderful organism, the insect 

 would not catch the active aquatic creatures on which it 

 feeds, and could not carry on its mission of destruction. 

 Perhaps the reader may have visited an aquarium, and 

 seen an octopus in motion. Like the dragon-fly larva, it 

 crawls slowly and almost uncertainly, but, like the same 

 larva, it can shoot through the water with considerable 

 speed to a definite point, propelled by similar machinery, 

 and engaged on a similar errand. 



They are cannibals to a certain extent. They will not 

 attack each other by preference, as long as any other prey 

 can be found, but they cannot endure hunger, and in 

 default of legitimate prey, will attack and devour their 

 own kind. In fact, if they are to be reared in captivity, 

 each must have a vessel to itself. Put two into the same 

 vessel, and in a few hours they will have fought, and the 

 victor will have begun to eat the vanquished. 



I have noticed that they are always on the look-out 

 for insects which fall into the water. I had often 

 wondered why it was that flies, moths, &c., disappeared 

 almost as soon as they began to struggle, and it was not 

 until I had seen my own specimens seize their prey that 

 I found the key to the mystery. 



They came gliding up from below, not moving a limb, 

 grasped their victim and sank again, their grey bodies 

 being curiously indistinguishable in the water, especially 



