FISHES’ EGGS 15 
Next, he seeks the lady of his choice with the purpose 
of inducing her to lay her eggs in his nest. First, he 
tries to persuade her, swimming round and round and 
advancing before her, but should his blandishments fail, 
he suddenly becomes annoyed, and erecting the spines 
on his back he endeavours to drive her to the nest with 
several well-directed nips from his powerful jaws. 
If, during these endeavours to persuade the lady to 
visit his nest, a second male appears upon the scene, a 
battle royal ensues. Brilliant in colour and bristling 
with rage, the jealous fish bite and chase each other 
through the weeds. At the conclusion of the fight the 
vanquished combatant, immediately losing his brilliance, 
slinks off to his own quarters, while the victor, becoming, 
if possible, still more brilliant in colour, advances to the 
female stickleback, who has been demurely watching the 
fray, and without much difficulty persuades her to visit 
his nest, and deposit her quota of big eggs. 
The nest, when completed, is a tube closed at one 
end. But whereas the male used to back out when 
leaving it, the female, after laying her eggs, bores her 
way through the closed end of the nest, thus converting 
it into a tunnel. This is a useful provision, for later the 
male fish aerates the eggs by sending a stream of water 
through this tunnel with a fanning movement of his 
pectoral fins. 
When ‘the female fish has laid her eggs, the fickle 
male drives her away, and, going through the same 
manceuvres, induces five or six others to add their eggs 
