How Animals Work. 



moving them about, bringing those in the centre to the 

 outside, and transferring those which were outside to- 

 wards the middle, so that all shall constantly be in 

 fresh water. When the eggs at last hatch, he then 

 mounts guard over his offspring, keeping the fry well 

 together under the safe shadow of the raft-nest, and 

 bringing back any that may wander outside its boundary. 

 Not until the young fish can swim freely does he relax 

 his vigilance and permit them to depart from the shelter 

 of the nest. 



A still more remarkable nest is built by the Rainbow- 

 fish, which lives in the rivers of Northern India and is 

 common in the Ganges and the Jumna. As its popular 

 name denotes, it is a very handsome fish, its body 

 brilliantly coloured with bands of scarlet and light blue. 

 The male Rainbow-fish also builds a floating nest, but it 

 is not composed of air bubbles like that of the Paradise- 

 fish, and is a much more complex affair. This little 

 fish selects the delicate, slender threads of those hair- 

 like water plants called confervae, which are to be found 

 growing in almost every pond and sluggish stream. 

 These threadlike plants are just a trifle heavier than the 

 surrounding water, and therefore are to be found drifting 

 at a little distance below the surface, if there is any cur- 

 rent to carry them along, or resting on the river bottom. 

 When about to build his nest, the little Rainbow-fish 

 rises to the surface and takes in a mouthful of air, very 

 much after the fashion of the Paradise-fish ; but instead 

 of forming it into one large bubble, he converts it into 

 a number of tiny ones, which he proceeds to expel from 

 his mouth in such a manner that they become entangled 

 in some of the floating threads of confervse, and carry 



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