THE THREE-SPINED STICKLEBACK 247 



Day gives an account, which has often been 

 quoted, of how some Roach were introduced into 

 an aquarium containing some Three-spined Stickle- 

 backs ; the prior inhabitants were dissatisfied and 

 forthwith attacked the new-comers, continuing until 

 all the Roach had been killed, when they were eaten 

 by their conquerors. Baker observed that in five 

 hours a Stickleback devoured seventy-four young 

 Dace, each about a quarter of an inch long, and that 

 two days afterwards it swallowed sixty-two. The 

 pertinacity with which they hold on to anything 

 they may have seized often causes their downfall, 

 children angling successfully with a stick and a 

 piece of thread to which a worm is tied. 



The Three-spined Stickleback breeds in the spring 

 or summer, the time of spawning varying consider- 

 ably in different years and according to the locality. 

 When the breeding season commences the coloration 

 begins to change, the dark greenish colour of the 

 back extending on to the sides in the form of 

 vertical bars, whilst the lower parts change from a 

 silvery white to a pale yellow in the female and a 

 brilliant red in the male. The males, who seem to 

 be much fewer than the females, select suitable 

 places for constructing their nests, such as quiet 

 shallows, or rock pools which are only reached by 

 the sea at high tides ; each chooses a spot at some 

 little distance from his neighbours, and commences 

 the building of a nest, first collecting together pieces 

 of the roots and stalks of aquatic plants and arrang- 

 ing these materials on the bottom, and then building 

 them up and cementing them together by means 

 of threads, which are of the nature of a mucous 

 secretion of the kidneys. The nest is made carefully, 



