THE SPAWNING-BED COMPLETED. 177 



one another. When one fish grows tired of its 

 work it drops down stream until it is refreshed, 

 and then, with renovated powers, resumes its la- 

 bours, relieving at the same time its partner. 

 The partner acts in the same spirit, and so their 

 labour progresses by alternate exertion. The 

 second bed completed, the female enters it as she 

 did the first, again depositing a portion of ova, 

 and drops a little down stream. The male forth- 

 with enters the excavation, and impregnates the 

 ova in it. The ova in the first part of the bed 

 are covered by the sand and gravel dug from the 

 second being carried into it, chiefly by the action 

 of the current. The excavating process just de- 

 scribed is continued until the female has no more 

 ova to deposit. The last deposition of ova is 

 covered in by the action of the fish and water 

 breaking down some of the gravel bank above and 

 over the nest. Thus is formed a complete spawn- 

 ing bed — not at once, not by a single effort, but 

 piecemeal, and at several intervals of greater or 

 less duration, according to the age and size of the 

 fish, and quantity of ova and milt to be deposited 

 and emitted. A female salmon in its third year 

 has a larger quantity of ova to deposit than a 

 female grilse, or young salmon in its second year ; 

 and it may be taken for granted, that the older 

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