STICKLEBACKS. 123 



himself beneath, does his best to drive in his 

 spear, if the other be not quick enough to dart 

 upwards and escape the thruSt; thus squaring 

 they fight round after round until the death or 

 flight of one ends the combat. 



I have often, when tired, lain down on the bank 

 of a stream, beneath the friendly shade of some 

 leafy tree, and gazing into its depths watched the 

 sticklebacks either guarding their nests already 

 built, or busy in their construction. The site is 

 generally amongst the stems of aquatic plants, 

 where the water always flows, but not too swiftly. 

 He first begins by carrying small bits of green 

 material, which he nips off the stalks, and tugs 

 from out the bottom and sides of the banks ; these 

 he attaches by some glutinous material, that he 

 clearly has the power of secreting, to the different 

 stems destined as pillars for his building. Dur- 

 ing this operation he swims against the work 

 already done, splashes about, and seems to test 

 its durability and strength ; rubs himself against 

 the tiny kind of platform, scrapes the slimy 

 mucus from his sides, to mix with and act 

 as mortar for his vegetable bricks. Then he 

 thrusts his nose into the sand at the bottom, 

 and bringing a mouthful scatters it over the 

 foundation; this is repeated until enough has 



