How Animals Work. 



which we have certain knowledge." The Stickleback 

 appears either to find a suitable growing tuft of sea- 

 weed in which to build, or to collect together some of 

 the soft threads of green or red seaweeds, joining them 

 to the stouter fronds of coralline growing on the rocks 

 so as to give the structure additional firmness and 

 stability, the whole being woven together by the silky 

 threads spun from the secretion of the kidneys. When 

 completed the nest is somewhat pear-shaped, and some 

 five or six inches in length. In this remarkable struc- 

 ture the female deposits her eggs, and then departs, 

 leaving the male fish to mount guard over the nest until 

 the young hatch and make their escape. 



Several tropical fishes are very expert builders, and 

 one, called Gymnarchus, constructs a very large float- 

 ing nest of grasses, about two feet long by twelve inches 

 wide. Three sides of this remarkable nest project above 

 the surface of the water, while the fourth side is about 

 two inches and the bottom about six inches beneath 

 the surface. According to the natives, the parent fish 

 guards the nest until the young are hatched and make 

 their escape. Another African fish, the Heterotis, 

 makes a nest some four feet in diameter, enclosed 

 by walls eight inches thick, made of grasses which 

 the fish removes from the interior so as to have the 

 bottom composed of the smooth, bare ground of the 

 swamp. 



The Chinese Paradise-fish constructs a most remark- 

 able floating nest literally composed of air bubbles. In 

 the breeding season the little male who constructs this 

 nest is resplendent in bluish green, with bands of red 

 and patches of orange. He may be seen to rise to the 



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