COURTSHIP AND NURSERY DUTIES. 117 



fore, producing fifteen thousand eggs. . . . After 

 spawning, the fish speedily recover their colour, 

 and to a great extent their condition ; the baggit 

 at once losing her dark complexion, and the 

 kipper discarding his hideous livery, his great 

 beak being rapidly absorbed, his sides becoming 

 silvery, and his back assuming a dark bluish 

 tinge." 



Pelagic eggs, as we have already remarked, are 

 carried about by the drift of currents. In these 

 currents we may distinguish two kinds, acci- 

 dental and purposeful. By the former, eggs are 

 seized and borne away to ultimately perish ; by 

 the latter, they are gradually carried to a region 

 favourable to development, and to the require- 

 ments of the larval fish. The plaice affords us 

 an instance of the nature of pelagic eggs, and 

 their dependency upon favourable currents. 

 These fish lay their eggs far out at sea, whence 

 they slowly drift shorewards, meanwhile develop- 

 ing. By the time they have reached the shallow 

 water bordering the shore the young fish have 

 hatched-out and remain in this shallow water for 

 some considerable time, when they slowly move off- 

 shore into deep water. The precise movements 

 of plaice have been carefully studied, and some 

 very important facts have come to light. It has 

 been shown that the eggs of the plaice laid off 

 the east coast of Scotland drift southwards and 

 shorewards till hatching time. The larva then 

 slowly move northwards along the coast, and 

 then outwards to sea as they reach maturity, to 

 lay their eggs in turn. Thus the breeding area 

 is kept constantly stocked. 



